I was very confused, because not only had I not done anything to fail the quest, I hadn't even spoken to Trudy or Ringo to trigger it yet. While walking through the streets of Goodsprings, the music sting played, and 'QUEST FAILED: GHOST TOWN GUNFIGHT' swept across the screen. I went up the hill to kill some more Geckos for him, survived his ambush, and then started to walk back to town.
After clearing out all the Geckos, I ran into Barton Thorn, an NPC I somehow managed to miss every single time I've played this game in the past. I finished the immediate intro and then headed to the Prospector's Saloon, and when I got there I decided to do Sunny Smiles' tutorial missions to get the free Varmint Rifle, even though my Guns stat is so low I likely won't be able to do much damage with it for a while. It was like coming home, especially compared to the aborted Skyrim replay I started and abandoned less than two hours in a week before. Almost immediately everything started rushing back to me, from the layout of Goodsprings to the locations of the skill magazines and snow globes I would need to pick up. I built myself a Speech/Lockpicking/Science character with a heavily INT-focused SPECIAL build and got started.
After reinstalling it and all the DLC, I started a new playthrough last night. After my 4000-word essay on Fallout 4 from a few weeks ago, I got a bit nostalgic for the good times I had in Fallout: New Vegas.
