Okay, I found the problem and it'll be fixed as of the next version. It's sorta-kinda a bug I knew already could potentially happen. The game was getting to the end of the list of if/else statements that told it what chat scenes to play, and then it would try to pull up one more scene after it had run out. With nothing else left in the list of scenes, it would just start reading whatever other code came next, which in this case just happened to be the entire dialog for that first chat scene. There was supposed to be an error message that played if the game ran out of scenes to pull from, but I didn't set it up right and the game just sort of went off on a tangent until something told it to stop, which in this case just happened to be the "return" statement at the end of that chat scene.
Luckily the fix is simple, I just need one or two more chat scenes. I was probably going to do that anyway, and also make an adjustment to the way the game prioritizes which chat scene to play. So this would have been fixed eventually. Probably. Maybe. I never would have found it without your help. So thank you!!