The short question:
How long did the phase last? Did he/she eventually stop, or did the behavior continue through potty training? Did you have to "do something" to stop it?

The long story:
My two year old is kind of potty training (a very child-led approach - she uses the potty for pee a lot, poop sometimes, but still wears a diaper and doesn't always tell me she needs to go when we are out until she's actually going. I intend to fully potty train in a few weeks/a month after our next vacation)....and has taken to stripping her PJs and diaper off at night. Sometimes because she has to go to the bathroom (so I take her if she calls for me), sometimes I think it's just because she can. It went on for almost two hours tonight - once she pooped for me, once she was objecting because there was a little poop in her diaper (I guess she wasn't wiped well), once she had to pee, and twice she just felt like throwing her diaper off). We tried several types of PJs, including zip up one pieces. I did not put them on backwards because they have feet.

I'm hoping not to have to buy footless 1-piece PJs (or cut hers, because they're pretty new and I've got another girl on the way!), but it may come to that!