ADE2.0 introduced several bugs and regressions.
One of these is that it quotes borrowing times above 1 week to the nearest week, rounded down.
Thus when the borrowing time is 1 week, 6 days, 23 hours and 59 minutes, it quotes 1 week.
Some eReaders are too stupid to keep track of date/time. My old Bookeen Opus was like that.
This is very handy on holiday, as it means they can't expire library books when they should.
Instead, they expire the library books the next time the device is attached to ADE (for example to borrow more books).
If you have a more intelligent eReader, it can probably give you the correct expiry time once you have loaded the book onto it.
If you want to reassure yourself, you can open the .epub file as a zip file and look inside.
You will find a file called rights.xml (probably in directory META-INF).
Open that and you will find a field that says something like
<until>2013-06-22T13:05:12Z</until>
(I don't think editing that field will extend the life of the load, though)