Yes.  It can trip if your glove or palm rubs against the collar as you operate the bike.  If this happens to you, you can rotate the collar about 1/4 turn in the throttle-off direction, and tighten it in the unlocked position.  It is less convenient to engage from there, but it will stay put.  To prevent this situation it helps to have longer grips and throttle sleeves, so your hands have room to work without touching the collar.