This is Clint, our 13-year old Labrador Retriever. I never did figure out what he was looking at. I stood right by him looking up and I didn’t see anything. Out of the corner of my eye, I thought I saw his tail wag, maybe as in “Ha! Made you look!”
Silly dog! (Or is that silly me?)
Ooh, now that’s interesting . . .
It's a long story ... 
Maybe he’s in contact with the mothership. Boomer used to stare at walls like that when he was that age. Listening to a different drum.