Hank isn't going senile.
He keeps having these little moments where something around the house isn't where he left it, or the milk carton in the fridge is empty and he doesn't remember finishing it. The whole time, someone's been breaking into his house and not covering their tracks properly. Or they want him to think his memory is going.
- Confirmed: his sister Steph broke into his house and has been living in the attic for weeks.
Stephanie is a previous incarnation of River Tam