Weird that he didn’t grin

Look away now if you are not interested in the niceties of editing and the pedantic predilections of writers..

My good friend Chrissie has been examining my manuscript with her beady eye and her critical brain, and writing lots of notes in the margin with her sharp sharp pencil.
Yesterday I came across a place in the text where I’d described a character as looking “pretty pleased” and she’d suggested I make his reaction more specific. This was a good suggestion. The phrase “pretty pleased” was lingering from the draft of the book that I had written in the first person, so that the  first person narrator was saying her husband looked “pretty pleased” about something. Now the book is written in the third person, “pretty pleased” does not sit well.
Chrissie suggested that instead of “he looked pretty pleased” I should say  “he grinned.” This is a perfectly valid suggestion and “grinned” is a perfectly acceptable word. But when I read the word I mentally shrank away. No-one ever grins in my fiction. They smile, they laugh, they smirk, they might even do a fake guffaw, or put on an evil pantomime laugh, but they never ever grin. Or…at least…to be more precise…I never describe them as grinning. They may, just possibly,  have an evil grin – so I may use the word as a noun, but I don’t ever use it as a verb.
Why? There is no straightforward explanation. I think it is because when I read that a character grinned, it makes it seem like fiction and not like real life (and thus breaks the fictive dream) because in real life I don’t describe (in my head) people as grinning. That may be it. Or - who knows? - maybe I just don’t like grin as a verb. It isn’t in my writer’s voice. People may grin in Chrissie's novels. They don’t grin in mine. Weird, isn’t it?
p.s. if one of you can prove me wrong by finding grin used as a verb in my fiction then of course I will give you a prize! ( this antipathy to grin as a verb may be very recent.)