But I certainly did think about it before using lowercase. The reasoning is this: The Uniform Commercial Code requires language opting out of implied warranties to be "conspicuous". In short, you can't bury the warranty disclaimer in the fine print. In a dozen-page long plain text license, putting the disclaimer in all caps might be a way to try and make it conspicuous. I enjoy Kyle Mitchell's take on this:
"Lawyers have long suffered under the delusion that writing anything in ALL-CAPS meets the conspicuous requirement. That isn’t true. Courts have criticized the Bar for pretending as much, and most everyone agrees all-caps does more to discourage reading than compel it."
In the Lil License, the warranty disclaimer is in normal type because the license is short, and it's meant to be read. It's a conspicuous part of the license. You noticed it right away ;)