Odd question about anal...?

Has anyone who has done or still does anal ever had a prolapse? Bit personal but is it something I should actually worry about or not? I've read up on it but it's not really clear how likely it is to happen? 
And I mean just a penis no fisting or any of that(!) 
It's just I'm 18 and did it for the first time today, didn't hurt much, my partner is fab and patient and actually listened and it turned out okay! 
But I don't really know what's what... 
Help? X