Teeth seem to grey out after scaling & polishing (Photo)

Had scaling and polishing done recently and all is well immediately after and 1 week check up. 4 weeks later I realized an obvious discoloration, made more prominent because of the existing crowned tooth colour. The crown didn't see any changes, but the neighbouring teeth all around doesn't seem to be as opaque and appears dull and greyer. Why is this happening and is this something which can be fixed?