We were dining at a restaurant (tasting menu $80), and the dishes were being served by waiters, with occasional assistance by men in chef's coats (not the star chef). At the table next to us, whenever the men in chef's coats would serve, the customers would respond with "Thank you, chef" as opposed to simply "Thank you". This sounded a bit odd to me. Then, I realized it was because the only time I'd heard this before was on Hell's Kitchen, when the contestants were being ripped a new one by Gordon Ramsay.
Is it customary in higher end restaurants to say "Thank you, chef" when being served by the/a chef ?