It's hard to say anything for sure. But I'd suspect the continuous work on marketing and/or the recent the changes to help reduce signup fraud (as well as working to speed the whole process up.) This is all pure guesses though. Could just as easily be people are getting more used to Steem/Steemits place in the market, or just some short term investments into Steem (which I'd guess we'd see it drop back down in the future.)

So in short...dunno. Lol. But I like it :)