your mother on 11 August 2012
A friend of mine reported a similar situation with another game on sale - his transaction was blocked because he was buying games in two different countries and his login IPs raised suspicions (he travels). He contacted Steam support, they replied in 24 hours (!) but by then the sale was over. They still applied the sale price towards the purchase.
As long as you explain yourself in a calm and collected manner (don't rant!), you should be fine.
