There is a question on PMSE that I've been watching. It's a shopping question. I planned to close it, but I wanted to give the community some time to catch it in the reviews and take action themselves, so I waited a few days.
I had the question open on my screen, and it had 1 close vote, which had been there for possibly 4 days. According to Jeff, close votes expire after 4 days. I'm not sure if this is accurate as I thought I read somewhere that it's based on views, but in this particular case, I can see in our review history that a 900+ rep user voted to close the question 2 days ago.
When I went to cast my close vote, I noticed the modal window that shows what categories close voters voted in was blank, so I refreshed the screen, and the close vote was gone.
Since it was only 2 days, and the question really didn't get a lot of views, I'm wondering if it is a bug, or if I'm just missing something about how this process works. It doesn't make sense that a close vote would age away that fast.