A lot of doctors will be suprised if someone walks over hot coals and afterwards has no blisters or burning marks. Yet, at Anthony Robbins seminars thousands walk over hot coals and most of them don't develop blisters.

The human body is complex there are a lot of real phenomena that can dumfounded doctors. If you think doctors are infallible you might want to read http://lesswrong.com/r/discussion/lw/nes/link_evidencebased_medicine_has_been_hijacked/

Whether you take that as evidence that magic exists is a different matter.