Remember he's only 6 months old and may have slipped a little in his potty habits. I would say this will probably happen until he is a year old. You are very lucky if he's housetrained by 6 months, they usually take much longer. Has there been a change in your household? Even a slight one would make a difference. Possibly his routine was changed and that's why he's pottying in the home. I suggest you go back to housetraining 101 to refresh his memory. Good luck.