To the OP, check and see if you are actually taking on water in the bulge. Dry the bulge out completely and check again after 24 - 48 hours of no rain. You may just have the Catalina smile (as mentioned). I have a 1977 C30 that "smiles" every season just about even after I patch it up with Marine Tex. I'm not taking on any water. Every season or so I grind out the old Marine Tex and replace it. But it doesn't take much of a grounding to flex the keel and the "smile" although superficial is back. If you’re not sure, get a second opinion.