I have a 428 that nearly did the same thing, I was using Failpro gaskets just like Chas, I had a
oil leak at the intake and took it off to reseal and notice the blue silicone slowly working its way into the intake port, I replaced with standard gaskets to fix the problem. Since then I have seen it on 3 other cobra's, all small blocks. If you do a search on Failpro intake gasket you will see it is quite common, my advice is to change soon or you will get a hydrostatic lock and bend rods or break other things.
Sorry for the problem, but you will overcome and it will be better.
David
