I bet you will be able to help it but I don't know if you'll be able to rid the bag entirely of the stain. Browse the FAQ section (cleaning threads) to see if anyone had a similar issue...or you could have the vachetta replaced?
I would try the baby wipes before magic eraser. Try wiping the lighter areas a few times, then let it dry. Once the color matches a bit better, try wiping the entire thing. I've gotten water spots before and was able to blend them in like this.