I've never heard anyone else complain about this but all my trousers get ruined in two points about where the sit bones are. Normally people only complain about the crotch seam wearing out.
I notice my saddle has a seam that would hit about the right spot when I'm pedalling to cause this. So either it's a design flaw that no-one else mentions or there's something wrong with my saddle position/pedalling technique/bum.
Any other Ridgeback users experienced this?