You're still a guest in this country and why should our officials not review your situation every so often when they get an opportunity? We all well know that student visas are incredibly mis-used and I would dare say that for every legit student using one in Canada, there are two or three scamming work in the country and not studying. Secondly, how can a student afford to be doing all this travel back and forth to the US on a student's budget? That would certainly also raise red flags if I were an Immigration Officer on the front line.

I/Os need no excuse to send you or anyone else to secondary. I for one feel the supervisor was correct to send you for a secondary for an update, but it doesn't sound like either of the junior officers were doing their job in auditing your presence here in Canada.