she does, in fact, like to poop alone

So for a couple of days, whenever she had to poop, she would tell me it was time for a nap. Since she barely naps of late, and certainly never of her own accord, that was something of a give away. What it meant, I learned, was that she wanted to be alone so she could go poop...in her pants...in her bed. She knows that when I put her to bed, she is guaranteed some alone time. Clever girl.
So, okay. I get it. Easily remedied. When she tells me it’s time for a nap, I just leave her in her room where I have placed her little potty and close the door. She can’t get out and since we have a separate playroom, there really isn’t that much to do in her bedroom. I wait five minutes and voilà! She poops in the potty!
We make a good team.
And we have no more pooping in bed.