I don't think it's an issue. Mine will stay on one side or the other for long periods of time. I was paranoid about my temps for a while because of it. If you want, you can get two identical hides for both the warm and cool side to rule that out, but I'd say it's probably not a big deal. As long as the warm side is the right temp, the snake will go over there when it feels the need.

What size is your BP? If it's just a hatchling, it may be the size of your tub is too large. If it's a few hundred grams or larger, i wouldn't worry.