Here is another pic

It's possible it was the hard freeze, but if it was covered, usually only the outside portion of the plant touching the cover would be dead, and the damaged part quickly turns dark and not a gradual yellow wilting like yours. It kind of looks like wilt, but the plant is so young, it might not be. I would probably remove the hopeless foliage (or not, you could wait a while) and hope for the best.....

This post was edited by edweather on Sat, Apr 20, 13 at 16:38

it looks like sun and windburn. If it just went from the greenhouse to a sunny day, and then some wind, and then some cold, wow for all that it looks pretty good. I would just leave it alone. It will recover.
if it looked good when you got it, then it's not wilt. it wouldn't show that fast.