No-one reputable would consider approaching any potential model under 18, as a general rule when looking thru model castings tend to go for over 24`s, older still, (so called mature) are/have more body confidnce and are more relaxed wordly wise and easier to get along with
With everything I say take care and have fun but stay safe.,
well firstly id assume from reading your posts etc ( and correct me if im wrong here ) that youre over 18 ? so its not like he's approaching VERY young girls or anything , and leaving a card isnt rally any sort of pestering , its just what people do ..
to be honest , a smile and a chat hardly seems anything to worry about , but if you ARE concerned get someone to walk you home fromwork in the evenings for a bit to make sure he's not hanging round , though i doubt it , from what youve written he just seems like a friendly customer advertising his buisiness :/