Not condescending, but too much fingerspelling is taxing especially when she was probably trying to speedily check you out of the line. Communicating via ASL requires at least a peripheral visual lock and fingerspelling usually obligates the other person to drop what they are doing and look at your hands until you have completed enough of the word that they can figure out the rest via context. This kind of confirms my suspicion:
The moment it was obvious you were starting to spell out “alphabet”, she had your meaning and cut you off to save you the extra work. I think I would have figured it out when you got to “I only know…” especially since you were fingerspelling the whole thing. I mean, if you are fingerspelling every single word, it’s pretty obvious what you only know
It really helps to have a hearing friend who knows the basics get you started. It’s easy to remember signs when you can make the connection between each particular sign and understand the derivation (i.e. the sign for “girl” uses the thumb to trace out a girls bonnet string - isn’t that just precious?).
My mother had the opposite experience when she was temporarily using crutches (after having broken her ankle). She was buying groceries, and basically nudging her cart along as she went, when a teenaged employee (think Squeaky-Voiced Teen from the Simpsons) came up and asked if he could help. She said thank you, but she was doing fine. He came back a few moments later and said, “I’ve been ordered to help you.”
That was a slightly different situation, though, since it was painfully obvious that coping with this injury was new and awkward to her.
