I too have had numerous bogus key operations (open trunk, alarm, etc.) all of which are obviously due to buttons on the remote being pushed while in my pocket. It should be noted that, unlike some other cars, the trunk on the 2009 and later CTS-V does not open noticeably (only enough to disingage the lock), so unless you see the message in the DIC or physically check it when out of the car, you are very unlikely to know that it is unlocked. I keep the remote in a pocket by itself with other keys in a key case and it still happens, Solution? Don't carry the remote on your person or be more careful.
You are absolutely correct about the trunk only unlocking and not swing wide open. Sometimes the only way I know the trunk is opened is the warning in my instrument cluster.
I thought about the Key Fob issue. But what does not make sense is that the trunk would re-open only when the door is opened.
You would think that if it was truly the Key Fob, the trunk would open randomly and should not be triggered by anything in particular...
Not knowing how the Key Fob actually works, I would imagine that there is an unique wireless "fingerprint" for each car/fob.
What I don't know is whether the doors and trunk each have their own distinct signal, or the car itself has one common "fingerprint".
If the doors and trunk have their own distinct identifier, then maybe the wavelength (?) may be close enough that opening one might trigger the other.
What seems more likely is that the car as a whole has a single "fingerprint", and when activating the door, there is probably some sort of power surge that triggers the trunk lock mechanism as well.
God, I'm such a fricken dweeb...