It could be the hug or it could be costrochondritis. Both of them don't feel too good at all, in my opinion. It could also be, like you said, a pulled muscle. We use our chest muscles more than we realize. It's not until something goes wrong, such as the hug, that you realize how much you use those muscles.

If it doesn't improve or gets worse, talk to your doctor regarding it as you don't want to miss something more serious. I hope you feel better soon.