Masturbation Question (pretty sure this belongs here...)

I had some time and decided to pull out my vibrator for a much needed 'me session' once I was finished I was looking at my toy and noticed blood on it...Once over the initial shock, I decided to use the bathroom and noticed a small (eraser on the end of a pencil, small) blood clot on the toilet paper along with a small smear of it as well. 
There wasn't an obscene amount of blood or anything, but still curious/concerned about what happened. 
Was I just too, um, enthusiastic? What else could it be? I finished my period about a week ago, so it's not that.