I believe this is an overall bug.
1. Click the select all check box to select all the check boxes in the inbox.
2. Deselect some of the items (I had 20 items and deselected 2).
3. Click Actions, Mark As Spam (Delete also does this).
4. When the items are gone the other items will automatically be marked as the top check box is selected still.
Desired behavior: If I select all items and then deselect any, or after I perform an action it should not auto select everything.