I have had this also but now when i test, it seems to be working ok.

i THINK this occurs when someone is actually ringing you. I have had experiences where i have gone to hang up and the phone has flipped. again i have just tested this and for the life of me i cant get it to falter but it has happened enough for me to notice this and seems others have too.

all in all wouldnt say it was a show stopper though