Sheldon and the couch? anybody ever noticed this?...?

so, i know all of the big bang theory fans will get me when i say sheldon has 1 place to sit and refuses to sit anywhere else, but when he first comes to penny's he has to find a place to sit, but then in episode 209 and 106 sheldon sits on the other couch without bothering? does this bother you that the role hasn't really stuck to his usual eccentric behavior?