Landing question. Experts Please

After getting approved in a span of 7 months from date of application, I just came back from CIC Buffalo (in the midst of a blizzard) to get my visa and COPR (and that of my wife and kids as well). My question is, when we land, will they check my current status in the US or that of my family's? My H1-B was already extended and will expire on March 2008 but we plan to land sometime end of April 2008. Will this be an issue with the Immigration Officers in the Port of Entry in Canada? I've read somewhere that they (the IOs) don't even ask for anything else other than the Canadian Visa and COPR and the rest of the requirements? True? Do I have to say that my US H1-B expired?