That's common in all service businesses these days. What it really means is "something(s) came along that pay a lot more--so your measly job gets bumped to the back of the que, but we're happy to hold onto it and keep stringing you along for the sake of future income."
That is one business model (and one that puts profit before customer service) but there are others, that some gunsmiths actually use.
It might just be "sorry its taking so long for us to get to your gun, but we have 180 guns waiting ahead of you".
Especially if you're looking at a one man operation. Sometimes guns wait weeks or longer AFTER work has begun, in order to get the needed parts.
This can be extremely frustrating and out of the gunsmith's hands. Especially when its a small low cost but unique part and there is only a single source.
I've been in a situation where the part was only $1.50 and took less than 10 minutes to install, but had to wait 2 months for the factory to ship one to my smith. Not common, but it does happen.
And,. of course the entitled customer blames the smith.....
One of my relatives was a full time gunsmith (50 years ago), very good at what he did, ran a one man shop in his garage, AFTER retiring from a full career working at the paper mill. Did repair work and GI to sporter rifle conversions as well as buying and selling used guns. Gave outstanding deals, too, as it was his hobby he loved, pretending to be a business.
Those guys were getting rare back in the 70s and damn few exist these days. IF you're looking at gunsmithing as a full time career you can make a living at, its a damn steep hill to climb for a long time.