My roof rack set up is a yakima base rack mounted on a 2008 corolla, I have two rocky mount tomahawks mounted to that. This weekend a buddy and I drove from Maine to New York for a bike race and when we got there the front Q towers had slid back 8-10 inches and both towers were loose. I called Yakima to see if this was a common problem and to see what I might be doing wrong. I was informed by Yakima that i have to tighten the roof rack ever 3-4 uses or every month or so which ever comes first. Is this normal rack maintenance?