I.G.
Nope, that has never happened to me. I order quite a bit on Amazon, so much in fact that I just recently decided to purchase a prime membership for the free two day shipping.
But even before that I always stuck to items with free super save shipping - I don't think I have EVER paid for shipping on Amazon.
I do try to buy from Amazon directly instead of Marketplace vendors if I can, mostly because it's easier to return an item or get a hold of customer service if something goes awry or I get a wrong size... but I have bought a lot of things from vendors lately and never had an issue.
I do think that it is important that you review your transaction before hitting submit... maybe I never had that problem because I'm cheap and I would never purchase something from a vendor that charges an arm and a leg for shipping.