At this one casino (indian res, socal) with an automatic peeking device (I'm assuming mirror, not red/green light), the dealer had a face up, then checked his downcard with the device. He proceeded to rearrange some chips in the rack and then checked the downcard again. I thought to myself-he can't have another face even though it was an automatic checker which would he theoretically would not know if it was a face. I hit a stiff as per basic strategy and came up with a 19. The dealer said "you made it" and proceeded to turn up a 7 in the hole, giving him 17. Is this just coincidence or do dealers sometimes know what card they have under there? In addition, I have also noticed that dealers sometimes check their hole card even if it is not a face or ace.