Am I overreacting or is this weird-?

My grandpa (not biological grandpa) said something I thought was odd, He goes "you know if I was 60 years younger I could be your boyfriend" *laughing*. I don't understand if it's a joke and like what he's trying to say? That he's old? That I'm super young? Am I overreacting? I just don't get why he said that. (that's the 2nd time he has said it, said it last time I was here too)
Am I overreacting or is this weird-?
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