Health insurer Humana announced late Thursday that the age mix of Obamacare shoppers wasn't exactly what the insurance plan had hoped for, with fewer-than-expected young adults signing up in the first three months of open enrollment. The insurer said in filings that the mix of enrollees in the 14 states where it sells has been "more adverse than previously expected."

Humana is one of the first health insurers to release information about its mix of enrollees. And, as we've written here before, the White House thinks its pretty important that about 40 percent of the people who sign up are under 35. So what does this portend for Obamacare? Probably not a whole lot. You actually see pretty significant variation, by state, in terms of what kind of sign-up numbers they're getting from the under-35 demographic. The District's exchange, for example, put out a release on Thursday showing a good age mix among its 20,000 enrollees.

That's only the experience of one exchange -- but, in the same vein, Humana's experience is only the experience of one health insurer. Carl McDonald, an analyst with CitiGroup who covers the managed-care market, suggests that part of Humana's poor mix could be about how it priced its products -- and says less about the overall market experience. He suggests that part of the reason why Humana has seen low enrollment among young adults was it decided to focus on plans with more robust benefit packages, which could be less appealing to a healthier crowd.

"It's worth asking the question of whether Humana believes the entire exchange risk pool is worse than anticipated," McDonald wrote in a Thursday morning note to investors, "or if the company's product positioning (low cost Gold plans in many markets and some regions where it had the only Platinum product available) is at least partly to blame."

And, as always, it's worth remembering the early enrollment period isn't the entire ballgame. Jon Cohn comes through with this helpful chart from Jon Gruber at M.I.T, which shows the Massachusetts experience with young adult enrollment. There, you saw many young adults wait until the end of open enrollment to sign up. Over time, the percent of people buying who were under 35 gradually increased.

We'll probably learn more about the mix of enrollees in the relatively near future. Many health insurers will be presenting their outlook for the industry next week at the J.P. Morgan Healthcare Conference in San Francisco (I'll be there, feel free to say hello if you will, too!). What would be most helpful though would be information from the Obama administration showing the age breakdown of sign-ups. The White House has said that it will provide this information at some point, but has not yet given a definitive date for when it will do so.