Loran, with you paying attention to planter maintenance (no lateral play in the tail piece) and the goal to have that distance approximately equal to your seed depth combined with your crop results I'd say that you shouldn't change a thing.

I would definitely watch your closing wheel down pressure.  Being that close to the seed especially you do NOT want excessive pressure which to put the Curvetines below seed depth. 

For most folks the approximately 2-3/8" standard spacer distance on the JD cast iron tailpiece is a safer setting.

Thanks for the picture. I'm glad these gave you your "best stand ever".

Jim at Dawn