Ammeter to Voltmeter...who does it?

I finished up my wiring project yesterday. At start up this needle in this volt meter twitched like crazy. After a couple minutes it settled down to a just above centered position with a slight twitch every 2 or 3 seconds. Turned everything on a when for a short drive. When rolling back into the driveway I noticed that gauge twitching rapidly again but before I could get parked it had settled back down again.
I assume the cause is only the voltage regulator functioning.
Anyone else seeing the same needle movement with a Sunpro volt meter ?

I have a Sunpro gauge set currently mounted under my dash....my volt meter twitches at times. I have a one wire Powermaster alternator.