
She has NEVER gone on the floor since she was fully trained. In houses without trays, she is fully house trained too so I doubt it is an issue with being indoors. It hasn't arisen for six months indoors with or without the tray.
To be honest, I am washing the whole duvet in the washing machine. I haven't a clue if it is biological or not. I should check.
It's a spare duvet in the living room to save on heating costs. It's been there for a while & she is very used to it. Just this past fortnight. They aren't little marks either but full on wees.

She did something similar when she was young whilst I stayed at my parents. I let her out of her crate in the morning & as I was unlocking the door to let her out, she had run off & peed on an airbed that I had been sleeping on.