For what it's worth, I appreciate having the door held open for me, and it still surprises me when a stranger or co-worker does it. I definitely make a point to say "thank you".
When someone knows they are putting me out (blowing past deadlines and/or asking me for something at the very last minute), I often will tell them that it's "no problem" instead of the generic "your welcome". I sincerely mean that I am glad to assist them, and that they should never hesitate to apparoach me - even though it may be an interruption.
I want to convey that I trust that they do their best to meet deadlines and respect their co-workers. So I'm going to clearly communicate a good attitude and assume the last minute request was out of their control (or an honest oversight). So, for me, "no problem" means "Don't give me any extra credit, & don't hesitate to ask in the future".
I guess I want to rant at the idea that someone could complain about words used in response to "thank you". Aren't gratitude and grace about "intent" anyway? Why can't we just accept that people mean well, maybe mean MORE than just "your welcome", and then not give it another thought? Who cares how they word it?
Ugh, more rules! I hate all these "RULES"!