I had the exact same concern when I started training in Arrows and when I bought mine. It's exactly the same behavior you describe.
High yellow during idle + taxi. Then during run-up it's in the green (after allowing engine to warm). Then during flight it's perfectly centered in the green.
Now that I've put a few hundred hours on it I've come to expect it, since it will reliably do that every time.
It also helps that the other 2 arrows that I originally trained in suffered from the same issue, and both CFIs seemed to brush it off as normal.
Given that you're also experiencing it in your Archer II, I'm inclined to think it's a piper thing...
I wouldn't worry about it at all.
Now... If it can't achieve normal range during run-up or in cruise, it's landing time