Years later, when another family member died and was buried near my grandfather, I walked over to my grandfather's grave and as I looked at it and remembered him, I completely lost it.
I was the same way when my grandmother died. She was the first of the 'close' grandparents to go. I even saw her during her last hours and didn't shed a tear...it was as if I was in denial of the whole situation. I never even cried privately.
Then, about two years later, I was cleaning underneath my bed and found a letter she wrote to me. That's when the waterworks finally turned on and I balled uncontrollably for the rest of the day. She said how much she loved me in the letter, and I was beating myself in the head for not telling her the same and being more appreciative. I think some people simply put the death of their loved ones in a locked section of their minds, refusing to look at it directly.
You never know when something will open your eyes and you're like, "Wow, they really are gone."