Forms update output before submit button shiny R

My form automatically updates the output before I press the Submit button. I read the description of "Submit" button and it says "Forms that include a submit button do not automatically update their outputs when inputs change, rather they wait until the user explicitly clicks the submit button". I am not sure if there's anything wrong.

For your information, here is my code. Data is from UCI (adult data)

Server.R

library(shiny)
library(caret)

predictSalary <- function(input){

  adultData <- read.table("adult.data", header = FALSE, sep = ",", strip.white = TRUE)
  adultName <- read.csv("adult.name.csv", header = FALSE, sep = ",", stringsAsFactors = FALSE)
  names(adultData) <- adultName[, 1]

  #Only select several attributes
  selected <- c("age", "education", "marital.status", "relationship", "sex", "hours.per.week", "salary")
  #selected <- c("age", "hours.per.week", "salary")
  adultData <- subset(adultData, select = selected)

  #The data is big, we only take 20% for the training
  trainIndex = createDataPartition(adultData$salary, p=0.20, list=FALSE)
  training = adultData[ trainIndex, ]

  set.seed(33833)
  modFit <- train(salary ~ ., method = "rpart", data=training)
  predict(modFit, newdata = input)
}


shinyServer(
  function(input, output) {

    dataInput <- reactive({

      age <- input$age
      edu <- as.factor(input$edu)
      marritalstat <- input$marritalstat
      relationship <- input$relationship
      sex <- input$sex
      hours <- input$hours
      data.frame(age = age, 
                 education = edu, 
                 marital.status = marritalstat, 
                 relationship = relationship, 
                 sex = sex, 
                 hours.per.week = hours)
#       age <- input$age
#       hours <- input$hours
#       data.frame(age = age, hours.per.week = hours)
    })

#     dat <- c(input$age, input$edu, input$marritalstat, 
#              input$relationship, input$sex, input$hours)
    output$prediction <- renderPrint({predictSalary(dataInput())})
  }
)

Ui.R

library(shiny)
shinyUI(
  pageWithSidebar(
    # Application title
    headerPanel("Salary prediction"),
    sidebarPanel(
      numericInput('age', 'Age', 40, min = 17, max = 90, step = 1),
      selectInput('edu', 'Education', 
                  c("Bachelors"="Bachelors", 
                    "Some-college"="Some-college", 
                    "11th"="11th", 
                    "HS-grad"="HS-grad", 
                    "Prof-school"="Prof-school", 
                    "Assoc-acdm"="Assoc-acdm", 
                    "Assoc-voc"="Assoc-voc", 
                    "9th"="9th", 
                    "7th-8th"="7th-8th", 
                    "12th"="12th", 
                    "Masters"="Masters", 
                    "1st-4th"="1st-4th", 
                    "10th"="10th", 
                    "Doctorate"="Doctorate", 
                    "5th-6th"="5th-6th", 
                    "Preschool"="Preschool")),
      radioButtons('marritalstat', 'Marrital Status',
                   c("Married-civ-spouse" = "Married-civ-spouse", 
                     "Divorced" = "Divorced", 
                     "Never-married" = "Never-married", 
                     "Separated" = "Separated", 
                     "Widowed" = "Widowed", 
                     "Married-spouse-absent" = "Married-spouse-absent", 
                     "Married-AF-spouse" = "Married-AF-spouse")),
      radioButtons('relationship', 'Relationship',
                   c("Wife" = "Wife", 
                     "Own-child" = "Own-child", 
                     "Husband" = "Husband", 
                     "Not-in-family" = "Not-in-family", 
                     "Other-relative" = "Other-relative", 
                     "Unmarried" = "Unmarried")),
      radioButtons('sex', 'Sex', c("Male", "Female")),
      numericInput('hours', 'Hours per week', 40, min = 1, max = 99, step = 1),
      submitButton('Submit')
    ),
    mainPanel(
      h3('Results of prediction'),
      h4('The predicted salary is '),
      verbatimTextOutput("prediction"),
      h3('Prediction of salary'),
      p('The application is designed to predict whether somebodys salary is greater or smaller than 50k. 
        The data is extracted from the adult data, provided by UCI database. In order to predict a salary, users need to
        provide information of the person whom they would like to make prediction on. After filling in necessary information,
        users will press "Submit". The information includes:'),
      p(' - Age: must be from 17 to 90'),
      p(' - Education'),
      p(' - Marital status'),
      p(' - Relationship'),
      p(' - Gender'),
      p(' - Total work hours per week: must be from 1 to 99')
    )
  )
)