Being Canadian, where we speak English, French and 'apologize", 'sorry' is pretty much a way of life. BUT - the prof is excessive. To me, it sounds like a lack of self-esteem - degrees and advanced education don't guarantee confidence. She may genuinely feel that she is troubling anyone she asks for assistance. I think the OP would be doing her a service to take her aside and have a quiet discussion about her excessive use of the word "sorry". I think just trying to 'correct' her behaviour by saying 'what for' or 'I'm just doing my job' is a trifle PA and may even embarass her and make the situation worse, from her perspective.
I agree with the bolded. I have a co-worker right now who sounds remarkably like this prof.And like this prof, her behavior makes her ineffectual and people view her as less than competent as a direct result of this habit.
Every time she comes into my office -- which is when I've asked her to come in to do necessary work -- she starts out with an "I'm sorry." Every time she needs to ask me a question, it's "I'm sorry." To make it worse, she also changes her voice to a very babyish, little girly, high-pitched tone. She has self esteem issues and was emotionally and physically abused by her late husband and I view her behavior as a leftover from those days when she had to kowtow and fear that if she spoke "wrong" she'd get a punch in the face.
We've brought it to her attention and response was... to apologize for doing it. So now, she starts out with, "I'm sorry and-- Oh, I'm sorry for saying I'm sorry!" All in that same voice.
I have so much sympathy for her, but it can get reallllly hard to take when she's saying it fifteen times in five minutes. I just view my patience as time off from purgatory.