Tonight I took my first Nook to the neighborhood Barnes and Noble - but experienced a couple of surprises when trying to use the in-store reading feature. So I want to make sure I'm understanding how this works.

- I found an ebook and started reading it. But within a few minutes I remembered something else that I'd wanted to search for in the store. When I went back for the first ebook -- which I found by searching for it again in the store - I wasn't able to open it. (This was about 15 minutes after I'd first started reading it, so I just moved on to another ebook.)

- That second ebook was "Nook Tablets for Dummies," and it described how you could put a Nook in sleep mode by very quickly tapping the power button once. So I tried that -- and then was unable to then re-open "Nook Tablets for Dummies" for in-store reading.

So if I want to read an ebook in-store, are there any things I should know about what I shouldn't be doing? (Because now I'm wondering if I'm supposed to be just reading the ebook, and if it's designed to stop being available if I stop reading the ebook and do something else!)