and I did not set scroll bars to 'always show' in the system preferences. if I flick my fingers and let the page stop scrolling on its own, the scroll bars never disappear. if I stop scrolling and then lift my fingers off the trackpad then they do disappear. this definitely did not happen until recently in the last month or so. it happens less often in the native apps (safari, itunes, mail, etc.) but most if the time it does. I find it very irritating.