Retrigger touch_start on state change. bug?

In another script I'm using State changes and touch starts to bring up Dialog menus. But every once and a while two menu would popup. In short found if you moved the mouse while you clicked the new states touch_start would be trigger in the next state. Found this very odd. So if you click and hold while moving the mouse on a prim, containing the script below, the script will jump back and forth between states. It this a bug or should the next states touch_start not to be triggerd from the mouse moving?

default
{
    state_entry()
    {
        llOwnerSay("default state");
    }

    touch_start(integer total_number)
    {
        state another;
    }
}

state another
{
    state_entry()
    {
        llOwnerSay("another state");
    }

    touch_start(integer total_number)
    {
        state default;
    }
}

EDIT:
quick solution use touch_end.