that wasn't a cheap bike when it was new. Should have been.

I don't know what to say about it. The seat stay is a utter horror story, can't believe they shipped that. The lug had a welding flaw, and they just let it go. Pressed lugs like these were made out of flat plate, shaped, and then welded down the centerline. That is the weld that wasn't completely made. There does appear to be a crack emanating from the welding flaw. I don't see how it would crack like that unless they didn't fully insert the tube into the lug -- which is entirely possible in this case.

I see what John is saying above, but I don't think it is an add-on, unless they filled a window.

I meant to say, I would probably ride it around town and keep it clean