How do you know everyone in that universe is aware that all are infected with the virus? Don't forget Rick heard direct from a CDC guy and shared with his group. Who would've shared with the Bob, the hunters, or anyone else?
On its face it is strange to start randomly talking to a stranger on the street. There's nothing wrong with it if you're a gentleman about it and time it well (small talk/witty comment/quirky compliment at a cross walk). And in my experience girls above a 7 are more receptive/polite about attention than girls
According to this "article" this guy got a wedding gift from his wife, so maybe it's not all that strange: http://www.businessweek.com/articles/2014-10-15/what-i-wear-to-work-morgan-stanleys-michael-outlaw