It's possible that you have the low gear limit set a bit tight. That causes excess tension in the shift cable, as it's stretched forcing the RD against the stop. Regardless of the brand a perfect low gear limit adjustment prevents overshifting of the chain intom the spokes, but is in fact a slight bit inboard of perfect trim. That allows the RD to move a bit beyond center trim for the shift and settle off the limit when the lever is released and it assumes riding trim.

Try backing off the limit a tiny bit to ease the cable tension to only that of the RD return spring. You should be able to manually push the RD in a hair (I mean it, only a hair) from it's natural low gear position. Double check that the limit will do it's job by shifting from the 2nd innermost sprocket to low, by pulling the bare wire away from the frame and making sure, 100%, bulletproof, bet-your-life-on-it sure that it cannot overshift.