I just got my TRX yesterday and I love it already (big upgrade from the BH thing). However, I have noticed a strange behavior that is repeatable, at least with mine. If I hold it vertically, tip up, and turn it on, it begins to beep/vibrate if I flip it over and point it straight down. Of course, a quick push of the button, and everything is fine again. It doesn't do this at any other angle, as far as I can tell.
Can anyone else duplicate this behavior? I might contact White's and at least mention it to them, just to see what they have to say about it.