Talking to a defeated boss causes the next random battle to register as a boss fight (cannot escape with run, dejon or tele).
More of a nitpick than an actual bug. I wouldn't even bring it up if it didn't seem like an easy fix (conditional statements, probably).
...Since I'm here, I'll add that when you leave Silveria the town music still plays on the world map. Overall, it's a good sign for the game if these are all I can come up with.