Becca,
I'm so sorry about your grandpa. It's no coincidence, though, that you saw him before he passed away...that happens so often. Without really knowing it, it was your goodbye to him. Though I know how much it hurts to lose him, among the other really sweet memories of him, you will remember being there at that time, and you will always be glad you did.
I absolutely love being with my grandmother. I know that since Mom died, she's afraid she won't see us kids much anymore since we all live so far away. All of us have made a promise (and we promised my mother) that we would look after Grandma and keep in touch, and visit as often as possible.
Your grandfather is not sick anymore, and that's a real blessing. Sometimes we hurt so much when we lose somebody, that we forget--- they might have been ready to go, and we selfishly want to hang on to them.
I know your grandpa is in Heaven riding around on a really sweet riding lawnmower!