Sounds standard behaviour 
They are such little .
We had a floor time menace - Megan (RIP) was a special needs piggy, she was blind and had serious neurological issues. She was such a wonderful girl with no prey instinct whatsoever so free ranged a lot - we were lucky enough to have her for two years after she was rescued form horrific conditions by Walsall RSPCA. Whenever she free ranged she used to poo in Mrs SB slippers - I've poo'ed in Mummy's slippers...
Not had that yet (fortunately), but after floor time I spend about half an hour on my hands and knees with a dustpan and brush searching for hidden poop. The other three never pee the floor, they always go back to their wee mini-cage and do it there. These bad boys need some training! But then you look at their wee faces (not that you can actually SEE Bobby's face) and it doesn't matter.
the hidden poop! I like that I am sure they hide some deliberately