I had the same issue when I bought my 2010 (was a few years old). Yes, the sunroof drain can be causing this, but the problem I had was much easier to fix. Took me a while to find it, and the entire front passenger carpet took a while to dry out and also had some mold to deal with under the carpet. After removing the plastic kick panel by the passenger's feet, I noticed that there is an access panel about 2"x4" that is supposed to be plugged with a rubber insert. If I remember correctly, it's partially hidden behind the computer that's mounted down there. The rubber plug had fallen out and was laying just below it. Without that plug, water being thrown up by the right front tire was making it's way into the cabin and soaking the carpet. Once I reinserted the insert plug, the problem went away. Not sure what caused it to fall out in the first place. Hasn't been a problem since.
I tried to find a picture or diagram, but couldn't. Sorry
If you see the plug/insert correctly in place, then I'd move to the sunroof drain issue next. Good luck!