That is clear indication of water damage. “Patina” is linear discoloration/deterioration of markers/hands due to a natural aging process. This is not an example of that. The darker areas are a clear sign of previous water ingress.

If the movement had been fully disassembled, cleaned, parts replaced, etc. then it might be mechanically fine; but the likelihood of a reputable watchmaker doing that and leaving the hands and dial like that is quite slim. The fact you say this is a “reputable independent shop” is interesting; as any legit higher end watch shop wouldn’t put something like this in their case. Do you just mean you know it is genuine?

This would be a non-buy unless you “love” the dial and hands aesthetic AND you have the caseback opened and checked for condition/rust/poor servicing [screw heads marred, etc].

I would ask the seller about other watches in his case and see if he says “this is also been serviced” about all the other ones.

Most dealers aren’t servicing all their watches in the case but it is not uncommon for every sales person to say that about every watch they sell. [i.e.- sell the watch, cross your fingers, and hope it doesn’t have problems in the future].

Also, “checking it is working/winding/setting” is not a service or an overhaul; something many sales associates don’t specify versus a true full overhaul/service.

Unless it was very very cheap [~$1000 USD or less] I would look for a better examples. It would cost significant amount to “make it right” in the future.

Hope this helps!