Checking usually only happens involving extremely cold temperatures. I just happen to talk to someone today that this happened to.
5 degrees is pretty dangerous. Do not open it, as you probably won't. I always take it out of the box pretty early-on because it's a wasted layer to wait on, I think. The key is to do the hand tap trick by having the guitar unlatched and quickly opening it to touch the guitar real fast before getting out quickly again. Don't begin doing this until the case hinges and the case itself are feeling nothing more than maybe ..cool.