If it is only a very mild drift right, I think it is probably the drain grade (crown) of the road. Try it again in an empty parking lot (flat) some early morning and see if it still drifts right.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.