Unfortunately, I see this a lot diving in areas where there is a high concentration of divers in a small some what confined area like Vortex, Blue Grotto, Athens Scuba Park, etc… It’s sort of like 3 is company and 4 is a crowd. Especially when there are students involved. I know that with my students I am very protective of them and some what territorial when it comes to there safety. I sometimes get a little on edge when other divers get too close. It also seems that some Instructors with classes are not always concerned with sharing already tight space with other divers and vice a versa. We too have had a similar incident with a rescue class in which we did not know they we only training. They were so realistic we asked to help and the Instructor told use to mind our own business….JUST RUDE! However, not too long ago at a park in Texas (I think) a student drown because other divers in the area THOUGHT they were doing a rescue class and they were in fact not. The point is, as divers we need to respect other divers at ALL times and be willing to assist them whenever possible.