It probably wasn't a good idea to get defensive with the border agent by saying to him "are you keeping tabs on me". I always try to keep it to simple no or yes answers. I've had some real assholes questioning me when coming back to the states, but it's their job to to try to get you off your game to see if your lying, acting suspicious, or nervous. My last trip back from Montreal the US border agent asked me to clarify that I drove all the way from NYC to see a concert in Montreal I simply told him yes. He then asked in a wise ass disbelief kind of way - so you mean to tell me that you drove all the way from NYC to Montreal to see a concert? I simply told him yes again. Then a few other yes or no questions and he went back to the "you drove all the way" etc., I simply told him yes again. He stared at me for what felt about 10 seconds trying to make me squirm and change my answer. It's what their trained to do. He handed me my license back and I was on my way, I have the enhanced license so I dont need to have a million stamps on my passport. Bottom line is to never lose your cool, never be a wise ass, and keep it to real simple yes or no answers at all times. No reason to make up a story about how you have a girlfriend that you visit. What were you in Canada for? A vacation, business, what ever the case may be. I've done the crossing by myself and have had them ask me in disbelief that I went to Montreal by myself. My answer was simply yes, how much money do you have? 3 thousand dollars, their reply - 3 thousand dollars?????? My answer was simply yes. Always keep it simple, don't answer a question with a question, keep your cool, and don't get nervous or change your answers to their questions.