Is this a square taper BB of the cartridge variety with one fixed and one free cup? If so it sounds like the non drive side wasn't done up enough.
Were the threads in the frame known to be damaged? for example some shops fit frame-saver type thread together BB which does not utilise the original threads in the shell. I would take it back to the LBS or whomever fitted it and see if they can tighten it down or apply something like a threadlock to prevent it coming undone. There are occasions where the NDS cup needs to be inserted beyond flush with the BB shell however the threads may have bottomed out if they were dirty and not chased or worse still if they just done it up anyway without ensuring a clean interface.
