squirrel antics

Ok, so I live in the basement of our big house, and my room is halfway in the ground and halfway above ground. This means that my bedroom window is at ground level.

Just a minute ago, I saw the weirdest thing: a squirrel climbing up my window. He just stuck his paws on the glass and sauntered right on up the window as if it were a staircase, or as if it were a coffee table But it wasn't horizontal. It was vertical! Like the window that it is!

Is this normal? Do they have little suction cups on their paws or something?