So I have an on going problem that I was hoping would go away but hasn't yet...

About a 2 months ago, I had my Burm out for some exercise and he ended up taking a dump on my wife's treadmill. (Cleaned it up before she got home and she never found out, so its all good) I think he must have got his kicks out of it because since then, he's only shat in my home instead of his own. He so determined to do this that he'll wait even a couple of weeks by then I just want to get him out to stretch but he ends up doing the same thing.

Anyone ever have this problem or know how to fix it?