Kids don’t know if something is good, bad, weird or whatever until they’re told. If you are fine not wearing clothes, and do it in your home, your kids wont think anything of it.
Mind you, I've very much been a late bloomer so my perspective is probably not representative.
Could you say if this was a fixed behaviour (ie they always sought a private place to poop), had a fixed location (eg always behind the couch), if you used a potty at the time, and exactly which month it appeared at so I can note it with my own observations. Cheers.