Can you help me understand my old dog?

Dakota is a German Shepherd. She’s 13 or 14 years old. She’s always been the best dog ever.
But here lately she’s been urinating in the house. In the past she’d never do that unless we didn’t let her out when we should have, or whatever. But she’s doing it now, sometimes right in front of us.
She always pees in the same place. We can’t really get angry. She knows better, and she’s contrite but….. she won’t be with us much longer so I just scold her and leave it at that.

OK, we have a “runway” of sorts made out of various area rugs, that runs through a strip of the kitchen, from the living room to the back door, covering up the linoleum. She has a bad hip, and sometimes has a hard time walking on the slick linoleum so we put that down for her.
The first one is a long runner, the second is a small bathroom rug, the 3rd and 4th are also long runners.
She always pees on the small bathroom rug. It’s usually in the middle of the night, so we get to step in it first thing in the morning.
I have to wash the thing almost every day. I’m just glad it’s not on any of the runners because I can’t throw them in the washing machine.
Well, I washed it three days ago and it’s been on the back deck drying. There has been a small gap in her runway since then. I’ve been holding back on putting the rug back down, wondering if she’ll still pee there, and thinking that if she does, I’d rather mop up the linoleum than wash the rug. But…she hasn’t peed once.

Is there something about that rug that triggers her or something? Any ideas? Thoughts? We can leave it off. She does OK with small stretches of linoleum.

We did ask the vet. He checked her for diabetes. She’s clear.