I keep getting huge app icons on iPad 3, running on Mac OS10.8.5
Check to make sure you haven't inadvertently turned the iPad's "Zoom" feature on. With it on, a three-fingered tap on the screen will cause the zooming.
To check, go to the General tab in your Settings app and tap on the line titled "Accessibility." Once there, look for the line titled "Zoom." If it's on, there's your issue - you'll need to turn it off to prevent zooming with a three-fingered tap.
Marilyn