I am not familiar with that module, but I notice two interesting things.

First of all the documentation says that select is relatively new. Secondly a little later it says that if a file is not updated for a while, that it has logic for checking whether it got truncated, renamed, etc. (Think of log rotation here.)

I would guess that either this is a bug with its select method, or else someone is moving files from under it, and it is not handling that well...