I don't think he's being mean. I think he's being respectful. He's saying you have no reason to have to ask permision. You have a right to ask whatever you want.
He wasn't saying, "Ya, sure, spit it out" He was saying yes, of course you can.
It is my opinion that the age will be an issue for him, so don't get your hopes too far up, but be brave, hope for what you want, and accept what you get. If he says no, realize that there is a good chance that in his mind you are too young. There could be no other reason beyond that. So don't feel too hurt and rejected if the answer is no, he may just be protecting you, especially if he does like you too. If he says no, ask him why (calmly, just Do you mind if I ask why? and really listen to his answer.
But good luck. I hope it works out for you
I miss read. I thought you wanted to ask if he liked you too and wanted to start something. Yes, ask if he would like to keep the guitar. Tell him you really enjoyed spending time with him in the band, that you think he was great with the guitar, and would like him to have it as a keepsake so he can remember.
That's subtly saying you like him, he can take that however he wants it