Catatonic Squirrel

I spent about two hours yesterday observing this squirrel that appeared to be pinned against a wall, frozen still, high up, near to the top of the building next door. Not a place where squirrels usually hang out. At first I actually thought it was one of our cats, it was making a meow kind of sound. Then it stopped meowing and the animal seemed to just zone out and freeze while clinging onto the wall. Was it in distress, stuck, trapped, injured? I don't know but after a while it just moved across to the top of the drainpipe and hung there for a bit. Then, whilst I was not looking it must've returned to earth. It was seen running across a nearby garden looking healthy and normal. I've seen many squirrels do lots of things (mostly attacking bird feeders) but I've not seen this peculiar frozen behaviour before. Answers and expert views on a postcard please ...