I just rebuilt my fender P-Bass a little while back. Put a new paint job on it... new bridge.. and new seymor duncan quarter pounder pu.. I haven't had a chance to play in the last 2 months so i put it together and never really played. I picked it up today and everything works correctly but i have a little hum till i touch my strings or bridge.. Is there a grounding issue with something? I didn't do a wire from the low side to the bridge as I have seen other do.. do I need to do that?