What would you think if your spouse’s new coworker/friend of the opposite gender seemed desperate to meet you and was even sending gifts?
I'd think that they want to be friends with you (: it's totally normal for colleagues to become friends outside of work and go to dinners and such with their families. my parents still keep in touch with their work buddies and go to lunch every month even after retiring!! I'd trust my partner, and I'd be open to the idea of adding new friends to my circle if they're people my partner cares about.