It's not really critical. PHP likes all variables defined before you call them in a function. I've caught most of them but one or two seemed to have slipped throught the net. It doesn't affect the plugin and won't cause you any problems (other than recieving the messages). If you log out of your dashboard your won't even see them.
But I will fix this. If you email me I'll send you an update with the varable all defined.