Puppy has a peeing reaction

Hi everyone, not sure how to address this behavioral issue I'm having with our 5month old puppy. We had some initial potty training issues but are definitely over them.

We take him to my step sisters and tie him up in the garage when going over for supper. We do this because it could be a few hours and don't necessarily want to leave him at home alone. This allows us to check on him and take him pee throughout the evening say over a 4 or 5 hour span.

Often though he tinkles on his bed or floor. This evening when going home he was jumping around so I told him to sit on his bed and he did but then started peeing while seated.

Would this be a nervous / abandonment reaction and how can I correct it.

Thanks.