Vacuum pump, regulator adjustment?

When I first bought my RV-6 (steam gauges & vacuum system) a few weeks ago, the first couple flights the suction gauge displayed normal, in the upper part of the green band (5-5.5 inches). The last flight I made this weekend, I noticed that at engine idle rpms, the suction gauge was showing about 7 inches, and as the rpms increased for takeoff and normal flight, it dropped back down to the upper green band, about 5.5 inches.

Is my vacuum regulator sticking or need adjustment? Is this the sign of a possibly clogged main inlet filter (it looks clean visually)? Or worse?

Check it closely. It may actually be dropping DOWN to read 7 and then coming up to 5. That would be a suction gage out of whack and maybe a mostly worn out pump.

It definitely sits on 0 with the engine off and jumps all the way around to 7 when I first start the engine and let it idle, and at taxi speeds. The pump has 255 hours TTSN, so I don't suspect it's worn out yet. That doesn't rule out the suction gauge however. Both gyro instruments are performing fine (except for the AI which normally sits at an 8 degree nose down attitude in level flight, and shows natural level when I pitch up to an 8 degree climb... but that's because the builder didn't buy the AI with the 8 degree panel tilt built in )

Bump.

Anybody else have any ideas why my plane might be showing excessive vacuum level at low engine RPMs and coming back down to the normal zone as the RPMs increase?