also consider when you tear the anal area you are taking the risk of causing a fistula which is a tunnel where a bowel movement can reroute itself causing infection and this can result in having to have surgery to repair and to clean out the tunneled area.this is not to scare you it is simply a fact. so if your bleeding continues ever how little i would see your doctor , also if you are bleeding every time you have sex in this manor it would stand to reason you need to be more gentle and slow down and be careful about the force you may be using.
It can be normal, but how much blood is there?? The anus tears really easily, but you have to be careful with that sort of thing. My friend was having anal sex with her boyfriend and she actually had to have surgury to stop the bleeding. I'm not exactly sure what was wrong, if he just really tore her or what, but I know she wasn't a happy girl for a while after! She was really, really sore. If its just a little bit of blood, I wouldn't worry about it. But, if its bleeding more and more, or if it won't stop, you should probably consider seeing your doc. Hope i've helped!!
katie