I tested it, and yes I have the same problem with the alarm, but I also have an other one.
Let me explain:
My phone is in the normal phone settings (so not car, silent etc, but normal)
I put on my Bluetooth and my Bluetooth headset, connect them etc.
After this I make a phone call. After I hang up, I switch my headset of and (but not necessarily) I switch of my Bluetooth on my phone.
The first call will not ring!!!!!
So you will definitely miss the first call after using the headset (and made a call!).
This problem will only occur when the phone is in the normal caller settings, and you must make a call.
Anybody who has the same problem??
(Bluetooth headset = Jabra BT 250v, phone= dutch vodafone)