I don't think he forgot his old training as much as he had some type of urgent reason or provocation for the change - a darn good reason in his mind, I'll bet. Using pads or newspapers is not natural for dogs so they adapt to them to try to please us. Going out of doors on the ground in a place of their choosing and best suited to spread their scent is natural to them. So when they adapt to going on things we place on the floor, I am sure at times with some dogs things come up that weird them out using pads, newspapers as the smells or sound of those things as they approach or walk on them are at times probably odd to them and a little suspicious to the more attuned dog so they just avoid it if or when possible. He may know that when you are home there would be immediate trouble if he missed the pad & went on the floor but when you aren't there, he can miss it in peace & quiet and satisfy his new need to avoid it at all costs.
So changing up his habits, places, etc. can help retrain him, even at his age.
__________________  Jeanie and Tibbe One must do the best one can. You may get some marks for a very imperfect answer: you will certainly get none for leaving the question alone. C. S. Lewis |