(((Emily))) - I think you did GREAT, and no, I don't think what you said to the counselor is a bad thing. Rehab folks are pretty good at not being manipulated, but they're human. Most are RA's, so while he may SEEM more mature and grounded for a little bit, it sounds like his true addict self is coming out and they are used to this.
He's young, he's in denial and still thinks the world revolves around him and what he wants. Good for you on not falling into his manipulative tactics, for seeing them for what they are. He may not realize it yet, but he is truly blessed to have someone who doesn't fall for the manipulation (said as an RA).
Hugs and prayers,
Amy