probably it's a hemmoroid (i probably didn't spell that right).

a couple of things could make this happen.
1) if you have had a couple of loose bowel movements recently or an upset stomach kind of diarea.
2) if you have been straining while you poop'd. this could happen.

probably nothing to worry about. keep the area clean, if you have diarea, then don't just wipe your anus, wash it after each trip to the bathroom.
make sure to keep it clean and dry.

don't strain while pooping.

no worries.
jasmine