Sounds like sun &/or windburn. The new forming leaves will be nice & green if it is.
My squash do that even if I harden them off after about a week of 24/7 outdoors. When they get new leaves, I pinch off the old ones.
Yes, its due to some kind of stress. The ones I had get snowed on did that. The new leaves look fine. Sometimes nursery stock will do that if it is not hardened off right. Give it some time. They usually send out some nice new leaves.