I was reading a time travel fanfiction earlier and it brought to mind a question I couldn't answer. I know it's likely that there isn't an answer in canon, but I thought I would ask and see if I missed something.

Up until Harry's first year, Voldemort was more or less gone for 10 years, right? And (unless you are going to turn Dumbledore in canon into a manipulative person) Dumbledore had no idea that his DADA professor was working for, at first, then later possessed by Voldemort. More over, it seemed that Voldemort at that point was working only through Quirrell. (ie he didn't ban together other DEs in order to get the stone) So it seems to me that the first indication that someone was after the stone was when Quirrell tried to rob Gringotts, right? So, how did Flamel and Dumbledore find out someone was after the stone and thus learn they needed to move it?

 

Dumbledore knows all...

 

The only explication I see is if It had just gotten into Gringotts, only for as long as some rudimentary protections could be put into Hogwart, and that there was a previous attempt on the philosopher stone at the Flamel's.

 

That still doesn't explain anything though. Sure, it is quite possible that the stone went from some unknown place to Gringotts to Hogwarts, but we don't know where Dumbledore or Flamel could have possibly heard about a plot to steal it.

 

They don't need to hear about a plot, maybe Vapormort tried to break into the Flamels and steal the stone directly from them. However, with them being over 600 years, they can drive off a ghost.

However, their recollection of the event makes Dumbledore think it is Voldemort, thus they know someone is after the stone, likely know whom is after it, and they need to protect it.
Who better than 'the only one he ever feared?'

Thus, the stone goes from the Flamels, to Gringott's as temporary security and then to Hogwarts.

Also, that was Quirrels first year there, in HBP Dumbledore says Voldemort placed a curse on the DADA position, nobody could hold it longer than a year after Voldemort was turned down

 

Maybe DD just realised that with Harry re-entering the wizarding world, It would be the perfect time for Voldemort to strike, and the Philosophers Stone was one perhaps many options DD thought Voldemort may take to return and decided to ensure its saftey.

 

That could be as well