I had a weird thing happen when I read the first three Wool books on my Sony reader. I downloaded them from Amazon (why would I do such a thing? well they were free!) and then converted them in Calibre. The files had extra characters here and there. They are not typos. For a long time I wondered if they were a secret code and I would scrutinize them closely. But I got books 4 and 5 from B&N and they didn't have these extra characters. I have no idea what could have caused this. Here are some examples, copy and pasted from Calibre:
had felt,>As with its floors and floors of apartments
“Do you think it was an accident? A fire or a power outag, be?”
The first year without angher, Holston had waited,
Although I have "bought" dozens and dozens of Amazon freebies, these are the first that I actually *read* so I have no idea if it happens frequently with Amazon books converted with Calibre.