Is it appropriate to ask professors to give you a mock interview?

Suppose that an undergraduate student is preparing for interviews for Ph.D. positions in natural sciences. Is it common/acceptable to ask a professor with relevant expertise and familiarity with the student's educational background and research ability to conduct a mock interview with the student as a way to ascertain problems in the student's preparation? Or will such requests be viewed as unnecessary or "asking for too much"?

I'm primarily interested in the acceptability of such requests in US colleges.