I think I know what you mean. I have owned a pair of both Boa and traditional lace boots. When I put the Boas on, I tighten the cable well but when I strap into my bindings, the pressure of the ankle strap on the center of the boot makes the cuff looser so I sometimes turn the dial again.
This happens because with a Boa cable the tension is mostly on the dial which is the only place you can tighten it. The tension of the cable reduces as the cable runs further down the rest of the boot.
When the ankle strap tightens over the boot, it squeezes both sides of the boot together and redistributes the tension of the cable, which causes them to loosen around the cuff area (at least that's what happens with mine. They are single Boas) So if you don't like it, you just have to re-tighten the Boa after strapping in for the first time and you should be good for the rest of the day.
With traditional laces, you can tighten the boot from each individual lace hook and then just secure it with a knot at the top, so the lace tension can be made even on each hook and the problem doesn't occur as easily.
If they loosen just from walking around, you have a problem. If it's just from strapping in, I would consider it to be normal and nothing to worry about.
Last edited by Gdog42; 01-03-2013 at 12:08 AM.