I live in Hawaii and go home to Vancouver 2-3 times a year. I never have trouble getting into Vancouver (maybe because I have a Cdn passport and am visiting my family). However, getting back into the States has been increasingly harder. It used to be a "wave through" a decade ago and now it's a much more intense interrogation. Last time I was hassled about whether I really purchased the amount I stated and no more than that. The customs agent really got into my face about it. Luckily, I had all my receipts ready to show him.