Good to hear it worked out. In case you were wondering why it happened the way it happened here's a brief explanation. When you tighten a truss rod it counteracts the pull of the strings. So if you have a dead flat neck and tighten it, you will get up bow (warped high in the middle, whether that's upbow or downbow). What happened in your case was that to counteract for the extra tension the heavy gauge strings put on the neck, you tightened the truss rod pretty far foward (or so it sounds). That's where the real danger is, so for not knowing what you were doing you got pretty lucky you didn't strip something out. Then when you switched back to light strings, all that extra tension just dissapeared, but the truss rod was still fighting it. By backing off the truss rod you eased the neck back into the position it is in at a relaxed state. If you get it dead flat and still have room to back the rod off, you can put a little relief in the neck (slightly lower in the middle), which some people prefer.