I travelled from Scotland to South London yesterday and the unit originally routed me through the M6 toll but then asked if I'd like to avoid toll charges. I selected "yes" and it successfully found an alternative. However, when I pulled up at a service station for a break on 2 occasions before the toll I switched it off as I took it inside with me. When I got back to the car I noticed it had rewritten the route to include the toll (i.e. the fastest route). Is this a known bug?