3.5 weekers and wet grass?

Would this be a good idea? I worked hard yesterday putting together a temp. pen for my babies to play in during the day (it's getting into the upper 80's-lower 90's here) but it rained last night So the grass is still all wet, and will be for most of the day in their pen since I built it under a tree so they could be in the shade

Would you still let them play outside today? They're 3.5 weeks old. I was just so excited