Is it normal to feel a seam in nasal bones that is still somewhat sensitive 3 years after rhinoplasty?

Palpable ridges on the dorsum of the nose after rhinoplasty: when the dorsal hump is removed from the bridge of the nose the arch that connects the left and right nasal bones is usually removed. This leaves an “open roof“. The nasal bones are there in fractured to close the open roof. If the bones are not quite close enough, or have drifted slightly apart, or a patient has somewhat thin skin the edge of each nasal bone may be palpable separately. In some cases one side may be more palpable than the other. As long as the bones have not separated to the point that the bridge looks wide there is no problem.

Hi and welcome to our forum!
During the procedure of rhinoplasty, the nasal bones are fractured and straightened. The "seam" you are feeling may be the free edge of a slightly displaced nasal bone. If it is not visible and relatively asymptomatic, it can be left alone. If the tenderness is significant, however, it may be wise to seek reevaluation by your plastic surgeon.
Best wishes...