Raised area under pat pending 18" lid vent?

[SixZeroFour]

Has anyone seen a raised area like this for the top vent before? I've seen it on larger kettles but never on an 18. I have a couple other 18s from the same time period that don't have it... This is the Cado I received from @fedex awhile back. (thanks again!)



I'm still looking for a set of lower bowl vents for this guy if anyone has some spare oldies.