[Tim Bishop]

Without seeing the bass, it's difficult to pin-point and be precise with an answer.

However, depending on condition of frets and how you store your bass when you are not playing it could be a factor. I always store my bass in the OHSC in a controlled environment when not in use. Smith necks are VERY stable, however, if exposed to the elements (i.e. humidity, temp changes, etc.) any instrument will pay the price. Sounds like you need a correct set-up. An appropriate neck and bridge adjustment most likely will correct your issue.