Although the main portions are locked up after hours, both places leave some racks of books outside in case you happen along after they close and desperately need a book. They trust that you'll leave payment for it (or return it, the library's case) appropriately.
On our last visit, we were also graced with a surprise visitor just before we left. It's quite a compliment to have a dragonfly light upon your finger, don't you think? A dragonfly also hovered between us when we took our wedding vows in 2004 (after we'd chosen Kate Spade wedding china with dragonflies on it too!), so I like to think they are harbingers of good luck.