/ic/ - Artwork/Critique

I use photographs from the internet all the time to paint from and so cases like this where Shepherd Fairey was sued for using an AP image of Obama to make propoganda art worry me.

I try to change the images around but ultimately you can see that one is based upon the other. It's pretty much my only source of reference material so how worried should I be? (I only get paid a tiny amount literally $50 per painting and the work is sporadic to say the least)