Hello! Today when I turned on the tank light, I noticed one of my Cories seemed to be stuck against the filter intake, but when I got near it, it effortlessly swam off. Nothing else about its behavior seems off- it swims around looking for food like all the others and doesn't seem any slower or different than normal, but occasionally it will go back to the filter and rest vertically against the intake. Again, it does not seem stuck nor injured by the filter, and it seems to be doing it voluntarily. I've had the fish for about 2 months now, and I've never seen it or the other Cories do anything like this before. I was wondering if this is just an odd quirk it picked up, or if could be a sign of something else. I know it's the same Cory every time, because the others are all albino's. Thank you in advance!