Sounds like crap to me, as there isn't a chance in hell I wouldn't use a thin film of RTV from the seal edge to the outside of the cap.
That "won't be round" thing sounds like BS also, because that's what the groove in the block and cap are for as well as determining clamping force around the entire seal.
I probably would be ok with those little ends as all they have to do is block that channel in the block.
I gotta tall ya, I would also clock the seal and a tiny little dap of red RTV on the ends where the seal halves come together.
Now I see why you decided to ask. :D
