Gotta ask. Before this happened, did you empty it and not replace it?
No, I have never done that.
The REAL dispute is the bathroom trash can.
She got huffy with me once about the trash can. She left the bathroom trashcan out once for nearly two days, sitting NOT in the bathrooom but sitting for two days beside the kitchen trash can because that was her non-verbal way of wanting me to empty it. But I detest "hints" and prefer people be straightforward, so I ignored the hell out of the damned trashcan out of my own resentment of her inability to speak plainly. And after two days she finally blurted out "Can you please empty that trashcan?"
I said to her: "Gee, thanks for asking," and I immediately complied right in front of her.
And then she proceeded to lecture me that when I first moved in she said she NEVER uses the bathroomm trash can herself, and only has it in there for guests. Therefore, anything in there must surely be my trash and not hers.
So from that day onward I have never ever ever again placed a single scrap of anything into that bathroom trashcan. Not one damned thing. If I blow my nose, I carry the spent tissue with me into my bedroom and throw it away in there (very easy to do since my bedroom is next to the bathroom). And if I replace the toilet paper roll, I likewise take the spent roll into my bedroom and toss it in there. Tampons, dental floss--all of it goes into my bedroom trash can.
So I believe this is her way of trying to MAKE me used the trashcan --even if it's just once-- so she can justify making me change it again.
If not, save them. Make a Christmas tree. Glue lights on the back side and put it up in her room. Then say, "Now let's talk about all the underwear you've been leaving on the bathroom floor."