Yes. I know someone who is 30 and hangs with younger people. She's holding herself back from meeting guys her own age and she acts immature around them. I'm younger than her and sometimes feel like I have to be her mother.
Now, I don't know who you are talking about, but the situation I know is not right. But everyone is different. You can have younger or older friends, but they do have an impact on you and if it's not beneficial, then it needs some attention.