Caesar sleeping with eye open?

Caesar generally sleeps under the couch or bed, however I think recently he's more open to the idea of sleeping ON the couch, or the chair, or even on the floor. Because of this, I have noticed that his favorite position is him on his back with his head angled in such a way that the skin is pulled back and one of his eyes remains open about 50%.

Its not the same eye each time, it really depends on which direction he is laying. I've tried to take a picture but the noises my camera makes always causes him to wake up and pick his head up. The eye which is open appears to water while he sleeps, however doesn't show any other signs of discomfort or watering while he is awake.

Does my baby just like to "keep an eye" on things in his dreams? Or is this something I should talk to my vet about?\

This picture isn't Caesar, but it reminds me of how he has his head against the ground. His eye doesn't remain open that wide either.