How do you comfort a grandparent? While not feeling guilty?

Okay that sounded bizarre but let me explain.

My grandfather lost his younger brother today and he's been sobbing on the phone with his family... I've never really been that close to him though but I feel like I should do something. And since my birthday is right around the corner I feel guilty because I feel like I'm taking the attention and he'll be forcing himself to be happy for me??? But I feel guilty and I don't know what to do.