The new Greenlight features are cool. Though, I'm not really sure what the point of "Ask me again later" is.
It apparantely brings the game up on your queue in a month's time.
I suppose it gives you a second chance to think about it.
It might be that you don't quite like the sound of it initially, but later on, if you come back to it, it might just interest you enough to vote yes.
Plus, consider the fact that it may be similar to many other games in the market or on greenlight at the time, and you don't want to vote for it because it feels a little too over-saturated.
But in a months time, there might be fewer games that are similar and successful and you might feel like this one could be alright and not be ignored under all the others.