I never made that connection.
It's possible that they knew each other, but it couldn't have been for more than a year.

http://en.wikipedia.org/wiki/Minor_D...n_Harry_Potter says:
Grindelwald was a Dark wizard before Lord Voldemort and his only mention is in Harry Potter and the Philosopher's Stone on Albus Dumbledore's Chocolate Frog card which notes that Dumbledore defeated Grindelwald in 1945.

Grindelwald is a Germanic name: Wald means "Forest", and Grindelwald is a ski resort in Switzerland.

The name Grindelwald also bears a resemblance to the mythic Grendel who was defeated by Beowulf. It is worth noting that one of Dumbledore's middle names is Wulfric - close to Beowulf. Given Rowling's penchant for clever naming, it is likely that this was intended.

http://www.accio-quote.org/articles/...t-anelli-3.htm says:
“…Owen…asked about Grindelwald... He said, 'Is it coincidence that he died in 1945,' and I said no. It amuses me to make allusions to things that were happening in the Muggle world, so my feeling would be that while there's a global Muggle war going on, there's also a global wizarding war going on.