So, I got a daily assignment located in an area I can't access yet. This is the first time this has happened in the several weeks I've been doing daily assignments. It's not a huge problem, but is this normal?
Yeah, it's normal. The daily assignments aren't given on an individual wizard basis taking into account which quests have an haven't been completed. Each day there is a single asignment for each of the level brackets KI decided on. So you may be "overleveled" for the area you are currently questing in according to whatever KI used to determine appropriate daily assignments for each level bracket so it's pretty common to be given an assigment that you cannot actually complete. Of course if you happen to have a friend who is willing to help you out you can always port into the area to complete the task, otherwise you'll just have to wait until you get one you can get to on your own.