I can give you a similar situation:
I had an employee keep telling me that I over react to certain situations. So I set her down and said .... what about my actions made you feel I was over reacting ? Did I yell, raise my voice, make threatening gestures, use inappropriate language ? No she said - you called in the person I was complaining about. I asked her .. well how else could I help mediate this issue ? Her response ... silence.
I think you need to ask the manager.... ( and be prepared and OK to hear an honest perhaps not wanted aswer )
Do I belittle them verbally by my use of words, sighing, being inpatient ? Do I roll my eyes ? is it possible that they are upset becasue they have to wait a reasonable amount of time to get a question asked.
For you to think about... Is it possible that the things that I am being asked are not really my responsibility to answer ?
Sometimes these things are becasue people end up with unrealistic expectations of what other staff should be doing. Good Luck !