Anal Sex... for the first time!

So my BF and I had anal sex for the first time tonight. It was actually pretty good. But as much as I love him he can be a total Doofus and he accidentally stuck his dick back into my vagina instead of my asshole. So now I am worried about getting an infection. He stuck it in my ass for a few pumps. Then i pulled off of it and he went to put it back in and that's when it happened. I pulled it out of my pussy almost immediately afterwards. It wasn't in there for long. Maybe 4-5 seconds tops.