Is it ok to have a friendship with an older coworker?

I’m a 25 year old female. I have a 60 year old male coworker who I have a good relationship with, nothing too personal and we don’t socialize outside of work apart from occasional texting to communicate about work.
We have worked on projects together which helped us build rapport. I respect him because he’s supportive and respectful. He’s a kind and funny person. We’ve got a lighthearted relationship. He’s become someone I trust and can talk to if I need help or advice. While I have a similar relationship with an older female coworker, I was wondering if my friendship with this male coworker at all sounds weird? I personally don’t think so, but I wanted to be sure whether it’s possible that observers looking in would think it may be strange? I personally don’t feel odd about it as I’ve never felt uncomfortable, at least not yet. I look up to him as a mentor. Are these kinds of relationships common or ok to have?
Is it ok to have a friendship with an older coworker?
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