tonearm/cartridge set up question

I'm new to vinyl and recently got the inclination to take a closer look at my set up to see where everything was at. Upon inspection I noticed the dropped counterweight on my JMW 9 arm was slightly off center, it was rotated about the axis formed by the length of the arm when viewed from the front. I adjusted it so it now hangs straight up and down, re-checked VTF and the cartridge (cheap Grado Red) is vertical when viewed from the front now. Problem is that I now notice a slight shift in imaging and soundstage, it's off to the left of center consistantly. I verified this with identical tracks on CD.

Did I screw something up? Should my cartridge not be vertical? I was present when my dealer set up my arm/cartridge and do not remember him making adjustments for this.

Any thoughts?
Suggest you check your antiskating force setting.
I suppose it could be an antiskate setting issue, as jameswei suggested. If in fact AS is set so high that channel balance is shifted to the L, you would probably also hear some R channel fuzziness or distortion, particularly on dynamic tracks near the outer grooves. Is this the case? If so, try reducing AS a bit. (On your JMW that means, unfortunately, unplugging the tonearm wire and giving it a counter-clockwise twist before plugging it back in. AS "adjustment" is not one of the JMW's stong points.)

That said, I'm inclined to another solution. You changed the angle of your C/W, which changed the azimuth of your cartridge. (That's how azimuth is set on a unipivot.) Incorrect azimuth affects crosstalk, which of course can shift images L or R. It seems fairly likely that the different sound you now hear is related to the change you just made.

You say the cartridge appears vertical when viewed from the front, but which part of the cartridge? The part that matters is the contact area of the stylus in the groove, which may or may not be aligned vertically with the cartridge body. This is very difficult to see. Dropping the stylus on a well-lighted mirror helps if you want to check visually. Another way to check, of course, is simply to return the C/W to the angle the dealer chose and listen. Many cartridges are not built square, including some much more expensive ones than your Red. It's quite possible your dealer was compensating for this.
The counterweight on my jmw9 tonearm is off center in order to give a level VTA.

Thanks for all the tips. I ended up looking more closely at the stylus rather than the cartridge body, which was a bit off. I then tried the twisting of the tonearm cable. I settled with a single twist of the cable and a slight offset in the counterweight to better align the stylus.

I think part of what I was hearing was the better (ie wider and more detailed) soundstaging of my vinyl set up over my CD player...which is a bit closed in.