It seems like a small library-related blog wouldn't be worth attacking, but if someone could get control of the server and have it to other things, then yes, it probably is. This applies to library websites, which is why I'm bringing it up here.
In my case, it was my own fault. I use WordPress to run this site, and had not been keeping up with updates. Even though things run fine with older versions and it's tempting to just let things go, it's always very important to keep web-based software updated - here's why:
When a new version of software is released, the developers usually list all of the problems it fixes in the previous version. This list tells the bad guys exactly how to exploit old versions of the software.
Then, all they need to do if find lazy people like me who haven't updated yet and exploit those vulnerabilities to take over your website.
So, and not to be all preachy about it, please make a point of updating your web software as soon as a new version is released. The server that hosts my website was crawling yesterday during the attack, and as soon as I finished the update last night, the speed immediately went back to normal.
Also: I'm sure this is purely coincidental, but on the drive home last night I heard on NPR how the Syrian Electronic Army has been attacking anyone they can, not just government-related websites. With those kind of bad guys out there, you can't be too careful.