My bullhead does the same exact thing....scared me at first. He swims up to my hornwart/pothos tangled mess in the corner of the tank (the crayfish keep tangling them up...I gave up having nice things in that tank lol..) wedges himself straight up and down in the pothos and then just sits there...sometimes all day. he uses the plants like a hammock lol.
Lol, my swamp darters will sit up in water sprite leaves for hours and just relax, I'm jealous