From what I understand of the current laws, and that is not too much. The short answer is yes, but you could fight it.
This problem is not just a 3D printer problem, this issue has been a major part of industries for many years and there have been many times in history where this has happened.
In saying this, there are always ways to fight and prove that you are the 'intellectual owner' of the work based on the date it was created by you. Basically if you create some thing, it is yours, though this does not stop some one from creating something that is similar and selling that.
I think the biggest issue around 3d printing is the 'Cloning' issues. that is when you create a design, there is very little to stop some one who has the skills to reproduce the design and print it. I must admit I am a culprit of this, though I always try and change the design so that it is unique to me. As 3D printing becomes more main stream, the laws will change to protect people/businesses from 'intellectual theft', may be even the cost of patents and copyrighting will reduce.
I am glad you have posted this question as it is something I am very interested in.

and, as always, Keep Printing

Pom