I've got a theory on that. More about the lack of continuity all together. In addition to the age thing, there are a lot of bizarre continuity errors.

• One daughter is replaced with another actress.
• His mother in present day is very sour and mean, and he appears to not be very close to her. Yet in flash backs his mother is very kind and nurturing and they share a very close bond.
• He has established one brother and three different sisters, yet in flashbacks he appears to be an only child.
• The actress that plays his mother in flashbacks also plays a woman he dates in the present.
• The same actor plays Louie's uncle in one episode and his father in another.
• Louie's sister describes his ex-wife as pale and blonde, but when we see her she is black.
• Fictional Louie's level of celebrity

The list goes on.

It's clear Louie doesn't care about continuity. But why? Because he's lazy? Forgetful?

I think it's because the show is supposed to be structured like a stand-up comedians body of work.

And when you watch a stand-up special, the comedian is free to pull anything out of his ass that will heighten the story he's trying to tell. He can just say "I've got a sister, she's kind of like this, and she told me..." whatever. And as we watch a comedian we aren't really keeping score on all this information.

We aren't stopping to say, "Wait a minute, you're talking about a girlfriend, but earlier you mentioned you were single."

Very few things are truly constant on Louie. The constant things are:

• Louie is divorced.
• Louie lives in New York.
• Louie has two daughters.
• Louie is a comedian.

Those are the constants, and just like in stand-up comedy, all the other details just sort of come and go as convenient, in order to service the most interesting, and most humorous story.