A few thoughts
Assuming the keel fit pretty well originally (new boat) then for a gap to occur like that there is some kind of moment causing the boat to rotate about the support position of the keel. In short is the keel only supported on a block of wood for a short distance? If that is not in line with the center of gravity of the whol boat then there is a tendency for the boat to rotate about the support block. Depending on how the cradle is sitting on the ground and supported this should not be surprising. For the gap to open up you definitely have some loose bolts or something going awry with the laminate of the keel stub. My O'Day actually had a very thick bedding compound between the keel and keel stub, probably 1/8 or more thick, as the bolts tighten it compresses this material and I suppose it gives it some "compliance" for shock loading. Not sure on the C&C but I have seen C&C owners scrape out the keel joint in the spring and recaulk them before as part of normal spring commissioning. If water is leaking out then it will definitely be leaking in when placed in the water.
Charlie Cobra did an awesome photo post showing rebedding a keel you can likely search on the site and find it, it was a few years ago. That would be my suggestion but not a trivial or inexpensive undertaking. It needs rebedding regardless of what else is going on. You might be able to have a travel lift just lift the hull a couple inches so you can see the bolt condition and rebed it. The bolts can lift way more weight than the keel but you need to tighten them in a pattern. Do not just torque one and move to the next, put a little torque on each one then move around adding torque to each bolt until they are all at spec, maybe go up like 5 or 10 foot pounds at a time. If in doubt and unclear of doing the work yourself get an expert, your dealing with a life safety item, loss of a keel can be quite catastrophic, check out George David in the Fastnet race this year, keel broke off and he spent 5 hours in the frigid north atlantic.