
Walking with your husband may have set him back as well, if he wasn't hearing the command a lot as it sounds like he was with you. It's like teaching a kid history at 15 years old and expecting them to remember a few years later :)
also, dogs can behave differently depending on how people behave around them; as an example, my brother owns (we use the word loosely) a doberman X rottweiler. When he wakls her, she chews at the lead for about 200 yards down the road, bouncing around and being a pain. Getting ready to go out, he always ends up yelling at her to sit.
If I walk her, she sits when I ask her to without needing to yell, she stops chewing when I tell her no, and she ignored other dogs - whereas with him she'll try to kill them. So being walked (I am going somewhere with this!) by someone different could easily have set his behaviour back (see!) the way you described. Makes me terrified of going on holiday!