I think this is likely part of the price you pay for one of the Chinese clones. I think I've got one of these on the second valve of my Mack Brass euphonium, but in a location (bottom, I think) where I decided it didn't matter. I have several on the pistons of my Wessex EEb tuba -- again not where they have any effect. And again, one or two are on the second valve. It made me suspect that the factory had some "second valve apprentice" who needed to develop better skills. Or maybe it is like the old Detroit "Never buy a car that was built on a Monday" warning.
While I'm a serious perfectionist myself, I have not felt the need to do anything about these since I quickly convinced myself that any obvious "solution" could result in there being a real problem instead of just a minor cosmetic one.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)