I have found that usually when we sense something is not "right", it isn't. When you're new to being in a relationship with an active addict, there is a learning curve. Learning to trust your instincts (they're there for a reason) will serve you well.
As for the "what if's" -- in my experience, my addict - after getting clean - would often get his dander up a little when I questioned him, or accused him on something. Then, he always came around to "I am the one to blame. I can't be angry with you for not trusting me; I put us in this situation". Only those statements when clean; when he was using, he ALWAYS lied and denied what I thought was clearly using behavior.