Don't judge a company by its tests, if they're easy for you to do it's not a slight on the company or the skills required.
At the time, I didn't realize _that_ was likely what they were evaluating, but in my experience interviewing engineers since then helped me realize what I'd overlooked.
I mentioned they passed on me mostly for transparency given the rest of my comment, but I can understand how it might have sounded otherwise. I liked their concept and stayed connected for a while after, not something I normally tend to do if there's bad blood.