Yesterday I posted a comment on a recent math.SE question that interested me, suggesting a "perhaps.. fruitful" approach. Later with a bit more insight I looked back and found the question had disappeared!
The purely mathematical nature of the question was not AFAIK open to doubt. It seems most likely the user who posted the question decided to remove it.
However the question was so interesting that I'm tempted to rephrase and post it myself, but a few nagging doubts occur to me:
It might have been removed because it's known to be part of some online competition.
It might have been removed as a homework problem, either by the OP or a moderator.
There might have been a glitch in math.SE that caused the question to get unlinked.
Is it something I should ask a moderator about before reposting?