What material do you have on the skids? That white ribbed rubber? That tend to grab on ally a bit when it is dry. You could try replacing it with the hard plastic skid material, slips a lot better. Also, make sure the skids aren't adjusted up to be taking too much of the weight. Weight should really be on the keel rollers, with the skids adjusted up just enough to stop it rocking. Oh, and i forgot to ask, what kind of rollers did you fit? The hard blue ones? Work best for tinnies, red is softer, and rubber is for glass boats, period, because tinny keels rip them up in no time. But you see people with them, because they are the cheapest.
HTH