A well endowed guy and balls-deep anal… what happened?

I’m dating a guy who is very well endowed, around 8″ long (honestly!). I’m a fan of anal sex, but usually I can’t take all of him in my ass. I can get around 6″ without too much difficulty, but those last two inches don’t really seem to fit.

Anyway, last night we were going at it, me on my stomach with him behind me, and he’s grinding around when suddenly he was all the way inside of me, balls deep. I was like, WTF, ZOMG, wow. It didn’t really hurt, but it definitely felt a bit odd, like he was so incredibly deep inside of me. I knew that I wouldn’t be able to handle any fast or hard thrusting, told him that, and he gently fucked me until he came.

So… the question is what happened to allow him to get all the way inside me? Did he straighten our my rectum or colon or something? Is this safe? I loved that I took all of him, and it was fun, but I want to make sure that I’m not hurting myself doing this!