unexpected green mails

Hi
I installed hobbit around a week ago and am very impressed with it but
I have a question.

I am occasionally getting a set of emails from it telling me things
have a status of green. These aren't after a state change as far as I
can tell as there are no other mails before them.

I am getting these once every couple of days, not at any particular time.

Can anyone suggest why?

ta

Robin