Chad,
You have found out that Epoxy and the summer heat don't really mix. Yes just the epoxy can cause that to happen. Dehydration can also cause that to happen. I became hypersensitive to epoxy/polyester resiens and would break out in a very itchy rash every time I touched the stuff. As a few have allready said, it is just something to watch out for and to keep the work area will ventilated.

Cheers.