I have an Aeroplan booking from NRT to YVR with a layover in SFO. First part from NRT to SFO is on UA and the SFO to YVR is on AC. My booking says I get 2 free checked bags but my searching for one way flights on Google shows a charge for checked bags for standard and basic fares. I'm assuming I get the 2 free checked bags but just want to check here first.

TIA
edited: layover instead of stopover