Met Someone The Same Weekend ...

Broke up with my girlfriend two weeks ago, kind of abruptly. She didn't even try to stop us like she usually does, so maybe she really did want this too? Either way, the same weekend it happened I met someone else... and we just sorta fell into bed together one night. Was it a mistake? Did my heart already break when I ended things? Honestly, I don't know... Anyway, he's a good guy, not looking for anything serious right now. Same as me really, just some casual hookups until I figure out if I want to be single or go back to her. But what about him? So... is this normal after an unexpected breakup? Am I just playing the field too soon or something? Does it matter?