There are evil Gremlins out to get your ebook reader! (See
Twilight Zone.) They exist everywhere and will attack when you least expect it.
You are extremely lucky, but the PRS-505 is a sturdy device. It appears to be somewhat more study than another available e-ink device (based upon reported incidents here), due perhaps in part to the metal that encases the PRS-505.
Glad you're enjoying the free ebooks, and thank you for the compliment. There are approximately 10 people (besides myself) who regularly work on making ebooks for our community. As you're finding out, there's really some great reading and some nicely formatted ebooks covering a wide array of subjects.
I'm glad you're continuing to enjoy the 505. For me, it's like discovering reading all over again.
Don