I don't think it matters how old you are.... I am 24 and I get the LOOK all the time.
I went into a preg group the other day and because DF is 29 but looks older I could hear people whispering about cradle snatching etc......
It doesn't help that he's 6'4 and I'm 5 foot....LOL
I just give them a scathing look back and laugh ..... it's all you can do!