There is a provider in Vegas that I see about once a year that I'll use as a reference. I've missed a year now and then, so there may have been times that it had been over 12 months since we'd seen each other last that I asked her for a reference.
But since I am a 'regular' of sorts, that's in my favor. If I were closer, I'd see her more often. I've given her Victoria's Secret gift cards as thank-yous for years where I've asked on more than a couple of occasions.
So, if these are people you've seen on more than one occasion and have made a little more of a connection with, I wouldn't find it too odd. Especially if you expect they will see you again. If it was a one and done kind of meeting, then perhaps he is one who doesn't hobby that often.
It all depends on the situation, I'd think.
I actually prefer using providers who are out of town for references. It gives less of a "I could see you again, but help me see someone else instead" vibe. Nature of the business, I know, but it's still out there.
I also try to ask providers that I will be looking forward to seeing again when they are back in town.
And P411 FTW