Posted: Tue Jul 17, 2007 12:32 am
The reason everyone keeps mentioning lopsided swimming, or any kind of leaning to one side or the other, is because during a respiratory infection the lungs may fill up with fluid on either side and in so doing weigh that side down. So any kind of sideways anything is cause for worry, and it doesn't necessarily have to appear while they're in the motion of swimming (I'd assume).
Like xsavingsaturdayx said, if it doesn't go away fairly soon, jump over to the nearest herp vet. The quicker you catch these things, the more likely they'll pull through.
One thing I noticed with my turtle, though (which is fairly young, as well...though not sure how old), is that over time he became a better swimmer. In the beginning I thought I was noticing all of these symptoms , such as lopsided-swimming and inactivity and swollen eyes (like a hypochondriac), and I had a lot of questions and worries and was in fact not sure what was considered normal for a turtle. Maybe it was because he got comfortable, or just learned how to interact with the water better, or I finally did enough research, I'm not sure. But everything turned out to be perfect.
So, on the bright side, it might be nothing at all.
Still, err on the side of caution.