i've read that several individuals have had problems with missed calls because the trackball moves (cannot be locked) while carrying it in bag, case or pocket etc. does Everybody have this problem with Every Pearl? and if not, how can it be avoided (besides reducing the sensitivity of the trackball). how do people carry these around and not miss calls? would a separate pocket in a shoulder bag which did allow for shifting of the unit while say running to catch a train be adequate? what how much of a problem is this really? thanks