Thanks to all who responded! I've had this frame for 19 years and had many great memory riding it so I'm happy that it looks like il be able to keep riding it. I was not able to get it to a frame builder, though talking to some on the phone and having them look at the pictures I'm more confident it's not a crack.

I had the bike repainted after 10 years and that wasn't my original intention but I'm going to have it repainted now at the same place – they can also weld it or do something if they are a little worried about the crack if the are concerned. They do a good job of cleaning up the whole frame and I think that prolongs the life of it. Considering I was going to spend $2000 or so on a new frame probably 500 - 600 on a new paintjob should be OK. Heres the bike shortly after it was repainted 10 years ago -