The issue is stemming from the slideInLeft class on the label housing the textarea. Removing that class actually remedies the issue. Specifically, it's the animation, as removing the -webkit-animation-name property from the class will fix the problem.
It looks like you're using a downloaded animation stylesheet. It may be more worth your time to just apply a patch, instead of trying to locate the root of the issue. One simple patch would be to put the border on the label and remove the border from the textarea. A couple inline styles and you'll be good to go.