Hello and welcome to the forum.
I feel very sorry for you both, having dealt with kidney cancer, and now having to deal with possible prostate problems.
How old is your husband?
His slightly abnormal PSA level could be caused by non cancerous prostate conditions, the MRI will shed more light on 'the state of play'.
I'm not medically trained but it appears very unlikely that the kidney cancer is connected any prostate issues.
Best of luck with the MRI and please keep us updated.