In all my years of crossing the border into the US, I have never had a problem. For a while I lived in Canada and worked in the US and went back and forth daily - never a problem. Show them my passport, show them my Visa and in I go.
I find the bridges much easier to cross than any airport.
Oh yeah, he is not an INS agent as some folks here thought, but a customs officer - quite a difference.
(why even FlyerAl has only had trouble crossing once going to BUF and that was when he crossed the bridge 2 x in 3 hrs).