I see that you've been on here five days. The score you have is good, and about "standard" for anyone who is fairly new but who has put some effort into writing "decent" Hubs.
What, exactly, goes into the author score is a secret because HP doesn't want people knowing how to "game the system" in order to get a high score. If you haven't done this already, searching for "Hub Score" or "Author Score" will get you more info on scores. (Or, you can just find it by looking over the "Help" section.) What we're told, though, is that a number of factors go into it, and how much someone "contributes to the site" is a big part. (I don't take "contribute to the site" as meaning having five thousand half-baked Hubs, but instead as meaning whether or not someone's contributions on here (in Hubs and to the community) add something to, rather than detract from, the site.)
Anyway, in answer to your specific question: Most likely, you've just been writing decent stuff and/or contributing to the community in one way or another. Everyone is different, of course; but in general, a lot of people start out with a low author score and see it rise into the 80's or 90's within a couple of weeks. (That is if they put in a "decent" effort, rather than do things they believe will raise their score(s), only to discover what they've done will cause it to decrease.) You're probably just doing what you're supposed to be doing, so it's reflected in your score (because, as I said, it doesn't take long to work up to a good score for most people who put it in a decent effort). Generally, Hubs, themselves, start with a low score and work their way up as people read them and vote them up, as they get views, any comments, etc. etc.