well, if they actually do, then i would take it as a very genuine, mature way of building a connection with you. i remember being a young guy and thanking my lucky stars whenever someone would do that for me, because they don't have to. if you're concerned with how genuine the person is actually being when they say "i stutter sometimes, too", then ask him/her to share their story. as a stutterer, i'm positive you'd be able to spot very quickly if he/she was just trying to be nice and they actually don't. if you care about the person and can tell they are just saying empty words, personally - i'd just address it, like "hey, listen i appreciate the thoughtfulness, but if you really don't struggle with a stutter, you don't have to pretend for me to be able to build trust and friendship with you. almost all my friends don't stutter; so please don't feel like we need that commonality in order to be friends. i just want you to be you and you to accept me for me. that's it." something light but direct