I purchased 7k onto my Amex about 6 weeks ago w/o problems. Two weeks ago I purchased $1200 on the Saphire Visa in my same account w/o trouble. Then, just this week, I did a $100 graduation card order to the original AMEX card, without a hitch.
I realise that this is not much information, but some of you are asking. All it tells me is that it is not an across-the-board policy to reject those purchases.