are you talking about the gap by your toes? in front of your toe cable?
i get the same thing on my dalbellos every now and then, i dont really know if it matters performance wise. but what i do is strap everything down to the tightness i want, flex a few times, then i un-buckle them all and push down where your booster/power strap is and the tongue will slide downish and fill that little gap, then i buckle the toe one first, then ankle, then top. it usually stays in place a little better after that. i find that a little less snow gets in your boots, when you get the tongue a little more flush.