I think that stub is of no real use any more, I'm assuming the antenna (under the cover) you are now using looks like this.
That metal cylinder is crimped to the ground of the cable which you have now soldered to your board. Note the active element (1/4 length) is the same length as the cylinder. So now you end up with a 1/2 wave dipole. You originally had only the 1/4 wave active element soldered to your board, I guess the stub soldered to the NEG was a low rent (cheaper) way to try to accomplish a similar result. Seems folks with X5's could try to duplicate it by simply soldering on a stub of wire to GND that's the same length as their antenna.