One Wheel Different to the rest

[Stash469]

I sold the wheels off my car at the weekend, so I took it to my local tyre fitters to have the new ones put on, old ones off. However, when i got back home and checked the wheels that had come off, one was a slightly darker grey on the part where the tyre sits, and on the inside. Also, the wheel weight was different on this particular wheel. I bought the car new (well ex showroom, had done 6 miles) and have never had the wheels off, untill the weekend. Anybody know why this might be?

[MartayMcFly]

Dealer might have just swapped a wheel rather than getting it refurbed, or might have had one wheel refurbed to match the condition of the other 3, or had the other 3 refurbed and didn't need to do the 4th... not sure when the car had only done 6 miles though unless it was somehow scraped in transit.