Im sorry that you lost your husband
you also sound very lonley at the moment and I hope you have some good friends to help you through this difficult time.
AND you always have us here at YT if you ever need to talk.
Because you arnt finding any pee patches on the carpet I think he may just be, as the others have said, excited to see you and pees a little.
I would talk this over with the vet.
If he is becoming incontinent then its not a huge problem.. my old schauzer cross is incontinent and she gets some drops from the vet which we put in her dinner every day to control it. Good luck.