I currently have a 56 plate GD with no rust on any of the original bodywork.
There was, however,rust on the bottom of the nearside front door that was repaired after a car park hit after which the door skin was replaced.
I noticed it after the three year warranty on the work done had expired by one week. The body shop,that the insurers insisted that I use, weren't interested saying,repeatedly, that it was out of warranty even though they agreed that the rust couldn't have happened in the last week.
The insurers weren't interested either but they didn't get my repeat business.
Vic.