My Cat Just Randomly Bit Me?

So my cat Patch is overall the sweetest of the 4 cats that we own at the moment. I know from my experience with cats that I'm definitely his favorite (won't go into why, but I just know. He's pretty obvious).

So anyway, just 10 minutes ago, he woke me up by coming onto my bed and being the pain in the butt that he likes to be and decides to climb all over my face. So I gave in and he snuggled next to me like he usually does an I started petting him. Now mind you, he's never had a problem with petting when he's comfortable and he was purring loud like he does. Well suddenly he freezes and looks off into the distance as I go in the stroke his head and he twists trying to bite me. Puzzled, I put my finger near his mouth, and sure enough he tried again. Then one more time, and he got me. Wouldn't let go of my finger, when I pulled it out, 2 deep bloody puncture wounds oozing red. So I pushed him off me and then he kinda snapped back to normal. Started meowing and crying like he does when he wants love and attention but I pushed him away for now, doesn't deserve it.

So why'd he just randomly bite me? There was nothing in the room to provoke him or anything.

Maybe he heard something (I didn't. Didn't see nothing either. And no, haha, our house isn't haunted).

It's usually and always has been (to me especially) a very loving and gentle creature and wouldn't no one, he doesn't hurt no one unless you REALLY, and I mean severely piss him off.

Thanks guys