It means that he found the 'fit' to be pleasurably snug, highly stimulating.
It means he felt the joy of a farmer, plowing fresh fertile fields of his own land, as opposed to the tedium and futility ( and/or danger ) of stirring a cauldron of hot soup with a swizzle stick designed in proportion for standard drinking glasses.
Next time he says you're 'nice and tight', tell him "I'm glad we
were able to fit you in..."
You could even add, "BTW So are you when you get in or out of a cold swimming pool"