Did you measure with the action open or closed? I have a very early Uberti Schofield, 1995, sn 529, and it has no cylinder play when closed and has .012". When open, the gap of .015". Many of these guns were shot with black powder, so the larger gap reduced problems with powder fouling.
These guns rely on the recoil shield to fix the cylinder in place, since top break guns always have a small amount of cylinder play when open. The extractor catch pin and extractor gear must have some clearance to work smoothly, so a slight gap is proper.
Your cylinder gap is very tight for a BP gun, so would quickly become sluggish with a couple of cylinders full. My guess is that the early guns were built to accommodate BP, but the company determined that nobody was shooting this powder, so maybe tightened up the gap.