Fingering accident

So me and my boyfriend were messing around in bed and he started fingering me super hard. We were both getting really into it and it felt great. Then he said he felt me really wet. He pulled his hand out and it had blood all over it. I went to the bathroom and I knew it wasn't period blood but I had no pain. I know when you are in that state you pain tolerance is higher but it was a suprise to find that much blood. Has this happened to anyone else? Don't know what happened.