My Touch has always had this problem, and I remember when I bought it about a year ago, there was a long thread here about page turn problems, and it seemed like it was a moderately widespread issue if you used the device for long enough in one session without restarting it.
I don't know if it was ever addressed though, because I've barely used my Touch since then. When I updated it last week it was still on 1.9.17, so it's jumped all the way to 2.3.1 without me ever using any of the firmware in between.
Guess I'll have to wait for 2.4.0 and see if that helps, or just restart my Glo every hour. It could still be a dodgy epub (the Glo and Touch have the same books on them), but I don't know any way of testing them. If definitely feels like a software problem, rather than the touchscreen itself.