I would kindly let the seller know that she shouldn't ever make assumptions about situations like this - that sometimes people are ordering the bare minimum that they need and would prefer to get a full refund so that they can buy the fabric from another seller.
I would not leave negative feedback unless she was nasty or cheated me or something. Anyone can make a mistake when it comes to customer service, especially at this time of year, when they're swamped with orders.
In exactly the same scenario, another customer might ask her, "Why didn't you just go ahead and ship what you had? It was only a half a yard! Now shipping is a day behind because you were waiting for me to answer what to do!!!!" :mrgreen: