This is not exactly creepy, but weird nonetheless.
My grandmother died suddenly. Healthy one day, gone from a heart attack the next.
About two weeks after her funeral, I had a dream that she called me. She was (cheerfully) aware she was dead and said just wanted to check on everyone. She asked a lot of detailed questions about those she'd left behind, which I duly answered.
She continued to "call" me once a month for the next six months "to check up on things".
However, with each passing month, her questions got a little more vague. She would forget more names, more details, and there were longer pauses between inquiries.
By the last month, she was speaking quite absently, like a person who called someone and then forgot why. She did say she loved everyone. However, I got the distinct impression that she was in a hurry to get somewhere or do something else. The dream never happened again.
To this day, I believe that (the universe/God/deity of choice) gives a person time who might have passed suddenly or was having trouble "crossing over" time to let go of the ties they had on earth. I am aware that might not comfort everyone, but it does me. 