Good lord! Now you mentioned it. I have a related experience.
So, I was in Vancouver sometimes back and I used to travel to USA at times with my work colleagues on official business. Meetings etc. I have B-1/2 visa in USA and we used to go via Peace Arch. So first time when we went, the border protection officer jokingly said, "go but only meeting no work! Don't press a single button on your laptop. No . A. Single. Button". It was quite forceful, but then I knew US immigration is like that. Somewhat brattish and having sense of superiority. That was all done.
We went another time in 8-9 months again. This time we saw something weird. The officer was very jovial, we much entertaining us etc. He said "Alright, so what do you folks work on?". One of us told him, "We work in ICT sector in CANADA." stressing on Canada specifically. He smiled and looked at me and said : "Great, so you guys must know a lot about computers, right?". I told him : "What my job in Canada needs, I know". He then laughed and added : "May be you guys can fix our printer back here. Huh? What do you say.". I smiled and we all shut up completely. He looked at us and told me to take my papers and go in a moment. We left there. We then discussed it among ourselves: That was underhanded. He was pushing our button to make one of offer a little help and then he could hold us for having intention to work in USA. That time I realized, VOs/Border protection folks etc use similar techniques that cops use for questioning.
I wont put it beneath the VOs to actually cook up a cock and bull story to probe the OP a bit. Entire thing might be a co-ordinated effort to put OP in a tough spot so he could be questioned and he or his wife ends up telling some part they had hidden or something.