Using OsmAnd v3.7.4 Android. 
The entire road on the Canadian side from Surrey to Chilliwack BC is shown as belonging to USA (in OsmAnd), yet in OpenStreetMaps it does show correctly as you pointed out. I have both British Columbia and Washington State OSM offline Vector tiles loaded. I just tried the OsmAnd online tiles and they show correctly. Perhaps it's an error within the offline tiles. If so we can resolve this issue.