the cutest thing

[strega]

Hallo,
I'd like to ask the meaning of a way of saying I just found in a text I am translating.
The context is the following: a man and a woman meet several years after the end of a very passionate relationship they had as students. The woman is now married to a very rich guy that she loves very deeply. They are talking about this marriage and the girls says:
'You think that after having you in my life, no other man would measure up, don’t you?' and then she adds: ' You’ve always thought you were “the cutest thing in shoe leather”. That obviously has not changed.''
My question is: 'cutest thing in shoe leather' means the best guy in the world or something like that??


'

[Anglika]

He was the sweetest thing, rather like a puppy or a kitten.

[strega]

Thank you.
Stefania