Smoke leak?

I just took the engine cover off and looked inside and everything looks pristinely clean so whatever leakthis is is staying right up on the roof and I'm starting to really wonder about condensation as the culprit. I did see a little bit of sheen around the smokestack flanges from the inside but it doesn't seem to continue on down to wheree it ultimately ended up towards the back radiator section. There were a few occasions where I missed the smokestack a little bit and I thought maybe it creeped around it in that respect so I checked the screws that hold the Smoke Stack Up and sure enough they were  not exactly tight ... I was able to get a good one and a half turns on each one. Still really doesn't explain how it rode along the radiator edges.

Still getting fluid along the sides of the radiator lid. This after not using it and letting it sit for the last couple hours. I am purposely let two drops roll over the edge of the smokestack to see if this continued, which it has. From now on I am going to make sure the drops go perfectly down into the smokestack and see if the residue problem goes away. I still cannot imagine that two drops would allow that much liquid to eek all the way to the back end of a locomotive, especially since I assume there's some sort of gasket there  at the stack to create a seal so it really shouldn't be happening at all.