Strange Kitty Behavior

This is Andy sleeping with his head in a flowerpot of chives. This is not the first time he has bedded down in one of my flower pots, but usually, he chooses one of the bigger pots where he can curl up his whole body while disturbing the placement of my plants and redistributing the soil over his fur, on the cabinet's top, and on the floor. See the shredded plant leaf? Also a sacrifice to cat behavior. 

Sleeping sitting up? This looks most uncomfortable. Does the curl in his back make it ache? Why is he doing this? I have padded cat baskets all over. Yes, the sun is coming in the window and is warm, but to stick his head in a bunch of onion grass? (Decimating the chives, too.) He is old, I don't know how old as he is a foundling, but could this be cat dementia? Today is the first time I've caught him at this, but now he has done it twice. Cats and kids -- expect the unexpected.
4/15/17 Update: Potted Cat