According to the rules:
Capturing a lumber mill does not constitute grounds for a restart.
Similarly, capturing an empty castle or an unguarded mine does not count as an encounter.
If you visit a friend, the door is open, but they are not home, then no encounter has occurred.
When, with a growth bonus on the first day of the week, Red captures an empty castle belonging to the opponent, what is the reason for awarding a red rush, if, according to you, no encounter took place?