Guys, do you use that to 'compliment' women you aren't in a relationship with?
No, whatever I don't know about dating, I know it's better initially to compliment someone on their style, personality, achievements, etc. rather than their inherent looks or how useful/sexy they are to you. Skirting the line, I appreciated when Ms BunnyBoiler complimented my abs. I wasn't born with those abs, by gosh, I spent hours working out to achieve them!
I also know people are quick to find reasons to NEXT someone they're not attracted to and to FORGIVE people they are attracted to. I think your 30s neighbor goofed on his approach AND you weren't particularly into the young'un to begin with.