Thanks for posting. I have never seen a crack at that particular location. It may have stopped permanently? It is hard to say if it was from stresses in the tubing that were caused by welding the top tube to the seat tube, or if it was from something else like your crash.

If the crack has stopped getting worse, that might bring up one more option. If you like the bike enough that you wanted to keep it instead of a new bike of a different model, you might ask if the lifetime warranty would still be valid if you kept the bike for several more years, and if the crack got worse later, then they could replace it at that time? If the bike shop or Trek or both say the lifetime warranty would apply in that case later, and if you decide to keep the bike, keep a written records of this with photos.

I had a Surly that had a frame defect, Surly refused to warranty it. That was 20 years ago, Surly was a new company that was pretty small at that time. Bike handled so bad I eventually put the frame in the recycle bin.

Six years ago I bought a new Raleigh, it had a slight bulge in a frame tube. After my experience with Surly, I was extra sensitive about warranty issues, so I sent photos to Raleigh. They said they did not think it was a problem. I told them, ok, but I was keeping a record of the photos and of my contacting them and their response in case the frame failed later, because the bike was brand new and should not have had a bulge in the frame at that location. So far it has not gotten any worse and it has not impaired handling or riding in any way.