When using iNotes and righting a long email - or getting interrupted as these days is the norm, its possible to be part way through your email and the session has timed out.
Now notes 8 seems to deal with this pretty well and pops up a message about your session expiring, allows you to click OK, then re-login, and you should be back to where you are (and it works - I tested it).
But when there is activity in the client like the user writing an email would it not be smarter (cooler) to do something to keep alive the session. Dare I suggest a small bit of ajax pinging the server every 5 minutes or so? It would probably only be relevant if a document was in edit mode and keystrokes were being picked up..