The firmware version that you have is giving the behavior that I would expect for the Join Indicator features (section 5.4 in the 1x2x manual). I would not expect a /RESET or power OFF/ON to send a Join Verification.
The behavior that I would expect from the 1x4x firmware version would be to send a Join Verification on a /RESET or power OFF/ON. The 1x4x firmware has not yet been released but should be available for download from our site soon.
Yes when the device JOINS the PAN it does send a Join Notification but when you /RESET or power OFF/ON the device it does not re-join the network. It simply stays joined to the network it was previously joined to (again this will change with the addition of the JV - Join Verification parameter in 1x4x).