Yes, it absolutely is. Some people just hate being honest if they think the customer won't like the answer. It's a bad way to run a shop, and almost always catches up with the owner.
One the other hand, there is the possibility that circumstances have caused him to get behind and he's doing everything possible to get caught up. It would be unfair for anyone to draw conclusions without know all the facts. Still, you have every reason to get frustrated. He should at least return your calls with a realistic completion date.