Well, since you asked…
ME: (after having a request fulfilled) "Thank you." THEM: "No problem."
Leaving me to wonder if my request would normally be considered a problem but JUST THIS ONCE an exception was made.
No problem does not acknowledge the expression of gratitude. My poor Thank you hangs in the air waiting to be completed by a You're welcome or an It was my pleasure or - dare I say - It was nothing; I was only too glad to...
(Miss) Edith Etiquette, just keepin' it real (civilized)