Could paint build up on a bottom bracket be considered a warranty issue? On Saturday I received the new frame for a steel xc bike I'm building up. I went to start on the weekend but noticed a large paint build up on the bottom bracket. The build up is about 15x3mm (don't have a photo) on the outer face and lip of the BB. This will require my LBS to face the BB before I start the build.

People I have spoken to at work believe that I should contact the seller (a major online retailler) about the build up as a warranty issue and see if they will cover the costs as one should reasonably be able to expect the frame ready to be built. 

Are there any common accepted practices that I should be aware of around this before contacting the retailler?
It is normal and acceptable for a frame to be delivered with paint needing to be removed from the bottom bracket shell, headtube, and seat tube areas.

It is assumed that a qualified mechanic with appropriate tools available will be assembling the bike, and that preparation of the frame is simply one of the necessary steps in the build process.

Indeed, most every bike company requires that the frame be assembled by a qualified mechanic (and in some cases by a mechanic certified by the bike brand) in order to maintain the warranty on the frame or the bike.

Unless there is something preventing the frame from being prepared properly, then this is unlikely to be considered a warranty issue.