The problem is you just claimed $50 which is far too low for normal leisure travelers stayed in the States for 4 nights.
I am an usual traveler and have never had any problem in going through the custom at all and I have never met anyone of them difficult. Ports like Cornwall, Kingston, Prescott, Niagara Rainbow bridge, far west side going to Michigan....never got stopped, checked or questioned in the last 18 years. Many times with my travel trailer loaded with groceries. In and out the custom 100 times and only being checked once when going into States right after the bus bombing in London which is understandable.