Mine was the same, it's very common, I put the head in hot water for a minute, stuck the edge of a table knife in the gap (it was perfect thickness for visor gap, so anything that fits right will work) then ran cold water over it with knife in place.
Took knife out and was perfect. Held in place with gap fixed.
You do not need cut anything off, it's the right amount of plastic it's just some manufacturing error that pressed it together. Again, very common error.
