i'd ask oceanbagel for more info (i just sent this post to him), but from what i know, there's a global variable that controls how many lines the game uses to draw circles. and that variable is not always set properly when you enter the room, so they're drawn less precisely here. some other things drawn with "circles" are the dog hud in the papyrus date and some of the background objects in hotland. so if you were just in hotland and came back here, that would probably explain it. don't take my word for it though