Younger men hit on me -- then get weird. why?

i am a 34 yr old woman. i get hit on quite a bit by guys who are 10 yrs younger. trouble is when i tell them my age they get all weirded out and act jerky about me. it makes me feel bad. but they obviously found me attractive enough to talk to me -- why get all weird about my age? i don't want to date them...but i don't need for them to make me feel bad either. does this happen to anyone else?