Many TSA agents don't know that Canadian DL's are valid SOP id, and either are trying to CYA, and notating an (invalid) exception to the rules instead of passport. Seen Hawaiian and Alaskan ids refused as well and the <deleted> demanding a passport to travel.

If any problems, a three striper <deleted> can be called to check the ID binder. But Canadian DL is valid for TSA regardless of where you're traveling (works miracously for renting cars in the US too imagine that ). LAX TBIT, LGA, LAS tend to be the most geographically challenged IME.