Getting null thrown as the changed object with Flex bindings and Air

Curious if anyone else has had this issue.

I'm using the latest Air build and have the Flex bindings library added. I had about 3 change watchers assigned to a string variable stored in a singleton object. I just added a fourth listener and now 'null' gets thrown as the changed object to two of the listeners. Seems to be a RACE issue. I was able to work around it by case: null but I'm curious if anyone has had this happen before.