Not obvious at all! This is the first time I've heard of them and I've never welded Ti, but searching for them on Google, yes it looks welded and filed down to me. I guess as on those early Cannondales people weren't ready for the look of an unfiled weld at the time. We've got much more used to them now. Maybe also their welds didn't look that great before they filed them... I've noticed on some Al bikes the welds seem to be filed in a couple of spots only, perhaps because that's where they looked a bit lumpy!