I'm seeing this also. In my case, it seems to happen if I have a webpage open then turn off screen using power button. It seems the webpage's activities (refreshing, flash, etc) seems to wake up TP. If I close the page, then no issues.
I never realized it until I tried to set a PIN-lock and then later decided to deactivate it and go again with the normal wipe. I think since then the screen turns shortly back on after it was already black/ off.