I've always thought of dogs being great judges of character - maybe something has happened and your doggy is not cool with older men now? Do you have any neighbour issues?
No, our neighbour is a 40 something guy and the dog loves him. Which made me wonder if something happened with this particular guy? When he came through the house the dog didn't calm down, which is unusual - once they're there he's usually relaxed. He even has no issue with DH's massive work mates. I dunno, I'm thinking it's possibly just this guy, maybe he doesn't like big dogs and didn't react well to him one time?

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