I know of no birders who have not had an i.d. questioned. That statement holds true of every member of state records committes I have met, too. Sometimes it was a valid observation; sometimes it was in error.
As stated above, it is to be expected. It is an essential part of birding. We are questioned; we question others. Critical examination is our "quality control."
That said, it is also true that we have no quality control on the quality control. There will be errors because there is rivalry/malice; the prejudice/bias against less-experienced and/or lesser known birders; percieved knowledge where there is ignorance (either by the observer or by the questioner).
It's really important not to take the questioning of one's i.d. as an affront to one's ability or to one's character. Objectivity is the goal. When personal affront/umbrage enters the equation, everyone loses--not just for that instance, but often in future encounters.
(I will go to the grave knowing it really was a Northern Wheatear!)
Phalarope