Cracks in hull of 2005 Launch 21V

[Brad2003]

At the beginning of the season I purchased a used 2005 Launch 21V with 400 hours. At the time did not notice any issues with the hull. We have put about 15 hours so far this season, and I have noticed a few hairline cracks running bow to stern in the hull's gel coat. One of the cracks is more than hairline meaning that when you run your fingers over it there is a difference from one side to the next of a millimeter. We use it as a pleasure boat and for wake boarding and skiing. All lake use, it has been in some rough water, but just boat wakes from similar sized boats. It sat in the water for 3 weeks in June, but since then has been kept on its trailer. Can anyone offer any insight as to why this is happening? And what is it going to take to repair? Also, could this be a warranty issue and would it still be covered? In addition, should we hold off using the boat until it is repaired? Or would it be ok to use through the end of the season? Only another month.

Thanks in advance for any help!