Um, excuse me. What? Why are you trying to hold the author accountable for your vocabulary? And since when are writers allergic to learning new words? Aren't words the basic building blocks of your trade? When you come across a new one, shouldn't you be tickled? Shouldn't you try² to add it to your own cache, to be pulled out on that day when you need not the right word, but the just-right-and-it-can't-get-any-more-per
With hundreds of thousands of words and loanwords in the English language, it's very unlikely that you are going to know them all. That's OK, though. Your friendly desktop dictionary or online equivalent is there to help you out.
Stop treating new-to-you words like the enemy and those who use them like show-offs. Coming across such words should be like stumbling on a gold mine, only there's no one there to fight you for the claim. Words are free game for whoever wants to use them. Use more and be happy! Don't begrudge those who choose to flash their bling³ from time to time.
1) And it was not one of those infamous five/ten dollar words. But even if it was, why assume that the writer's currency value is your own? One person's $100 bill may be someone else's chump change.
2) I say "try" because I don't think every word is a fit for me. No matter how I try to recall or use certain words, some of them just never feel right or come naturally to me. I assume other people are the same. However, the word may not be right for you, but it might be perfect for one of your characters. Just another reason not to disdain your new finds.
3) That's me using a word that is *not* part of my everyday vocab, and I pray to heaven that it doesn't become one. May the parlance of these times pass quickly into oblivion, replaced by words that sound less like baby talk and onomatopoeias for cash registers and gadgets! I'm only kidding, of course...kind of.