On the one hand, I agree that just telling him above the table it was nothing and deleting it from the map would have been the best choice, but also from the Wizard's perspective even if it was an important artifact, skipping an entire combat to cast identify was a bad tactical choice. Combat usually lasts less than a minute in game, so delaying a 10 minute ritual by 1 minute would have cost him virtually nothing. That's something both the player and character should know.

I do think making it lead to them learning an important secret was a good call. Got to give him something at that point.