Yes, you goofed. I kinda get your thinking--"Does S slightly prefer Mom's or Dad's place? I'll let him choose so he gets that +10% happiness." The problem is, you're making your S choose between Mom and Dad. He should never have to choose between his parents. The stress this creates outweighs any benefit asking his opinion might have offered.
Instead of worrying about snooping, I'd try not to tell S7 anything, either on these calls or while at your home, that he has to keep a secret or that you worry about mom overhearing. I expect Mom to be paying more attention to what you tell S for a spell.
