There ya go ! Thats gotta be it because i had a similar problem tho not at a perticular RPM, and i found them widened about like that. It's a bit tricky gapping Sgapped plugs so you may have thought it was at 30 but it may have been on the verge of too wide and only took a short while to wear wide enough to cause that. When you gap Sgapped plugs make sure to put the feeler in and move it up and down too find what angle yields the loosest feel and use that angle to set the gap. Otherwise you may gap it at 30 but the actual widest point may be wider than 30, a good bit wider possibly. The angle can vary depending on how short you cut them.
