Every time I revved the engine or went off idle, it would go into the red (overcharging). I was just making sure the gauge was working.
Then I unhooked the negative battery cable and removed the old mechanical (stock) regulator. I cleaned all of the grounding cables for the regulator base with sand paper and also removed the negative battery cable from the frame and cleaned that area. I covered these areas with dielectric compound and reinstalled everything. I hooked the battery back up and fired her up. It took a second for the volt gauge to move from the mid (straight up) position, but then it popped right over to the little line in the green bar. I revved the engine and it stayed right there. I turned on the headlights - it went slightly left of the bar and then came right back. Good deal! I took a drive for about 10 minutes and she never deviated from green.
Guess what's new in the engine bay? Regulator and starter (which I installed last week).
I figured the old regulator was overcharging so much that it was causing my headlights to blow from too much current or a spike. The last time one blew (at the Georgia Steel Soldiers rally in October) - it was the passenger side. I felt comfortable that the problem was solved, so I went ahead and installed one of my precious spare bulbs. I turned the lights on and the new one didn't blow, so it's good for now!