I had the same experience... I visited Montreal last month for a business trip, first time in a couple of years, and had 40 minutes of rather hostile questioning on my way in.
It didn't make much sense to me, and I assumed that they'd picked a middle-aged, grey-haired, white guy so that they couldn't be accused of racial profiling... but from comments here it seems it is a lot more general.
Some of the questions didn't make a lot of sense (especially not at gone midnight), one or two were personally rather insulting, and they seemed to think that I was over here for employment rather than business meetings.
Getting into China the following week, on the other hand, was a model of efficienty and politeness...
It didn't make much sense to me, and I assumed that they'd picked a middle-aged, grey-haired, white guy so that they couldn't be accused of racial profiling... but from comments here it seems it is a lot more general.
Some of the questions didn't make a lot of sense (especially not at gone midnight), one or two were personally rather insulting, and they seemed to think that I was over here for employment rather than business meetings.
Getting into China the following week, on the other hand, was a model of efficienty and politeness...