If it were me I would continue to be there for my friend. Maybe he was just having an off day when he sounded bothered. Let him know that you care about him and that you will always be there for him.
I have cancer... Don't stop talking to him. It's tiring and hard to act normal and happy all the time but we need as much support as possible.
Just keep doing what you've been doing, tell him whether he likes it or not, you're not going anywhere
His moods/emotions will be up & down...be there for him!