Is it possible that Rolex Green Sub "Y" series must have Flat "4"?

[kid_joe]

Hello everyone
I've been a member for years but rarely post

one of my friends just bought Green Submariner "Y" series
but there are some odds about the watch so I need comments from you guys.

the watch is "Y" series with mark i
and the case was engraved Y7xxxxxx & 16610T should be green sub for sure
but the heck is the watch's bezel ( color , pointed 4, closed 5) which seems to be matched with green sub later than F series ?

here is the photo of the watch




my question is if possible this watch was switched with wrong bezel?