I don't think okay is the word I'd use, but I would say it's
predictable that Lefty would growl with someone hovering right
above his head like that. He's showing he is very uncomfortable
in that situation. (Many other dogs would be also)

I would just keep that in mind & accommodate Lefty as you
would a human friend who had a particular dislike. Avoid letting
this situation happen in the first place if possible.