Teenage DD has started to say this, in a clipped monotone, as a method of shutting us down when we point out that her bedroom is a tip and we expect her to tackle it before swanning off to Primark or wherever. I think she thinks it sounds grown up and assertive and will set us back a bit. Or it could be because we pull her up if she keeps on saying 'I know' 
The only other place I've come across 'I'm aware' on its own is in written dialogue by an author who likes to keep abreast of how the bright young things and city sophisticates are expressing themselves, especially online and in US contexts - but sometimes gets it slightly wrong or overuses these irritating little quirks. I am working on this author's books as part of my job, not reading them for pleasure.
Just wondering whether anyone else is hearing this in the wild?