Another variable is that the sticker on the seattube might mean that the seat tube is that tubeset or it might mean the front triangle or all 9 tubes are but you can't tell until you cut it up. I have also found big blobs of brass in repair projects once I cut them open. Framesaver might account for some difference as well as paint/powder coating. No idea how much.

As a builder would anyone send back a tube that was more than 15% heavier or lighter than the spec? What about if other specs were significantly different? And yes, obviously if the wall thickness is thicker, the tube will be heavier so, you have compounding 'out of spec'-ness.

I have sent back/complained about fork blades that didn't seem right - the supplier sent me new ones immediately.