Why are my youtube subscribtion videos being marked as watched, when I haven't viewed them yet?

Ok, here’s what’s happening:

When I am signed in to youtube there are videos from channels I am subscribed to that are marked as watched… But, I haven’t watched them. It’s a little creepy, and it’s been going on for a few weeks now. And I know I have never even clicked on them.

Is this just a random error, or has Goldilocks been watching my videos when I’m out?

Has anyone else noticed this on their youtube? What’s going on?

I realize this question is likely going to be an Orphan on fluther, but I thought I would ask just in case anyone knows. Thanks.