It's just a question.
I completely agree with Quath about being courageous, and just telling him about it. Trust me, I hid flirtations and thoughts of relationships with other girls from my gf, and it was horrible! Horrible because she found out on her own! Had I told her straight out, I learned later, she would have been fine with it. We're now at the point where I have the option to see other people, but I had to work really hard to regain her trust.
You have to decide if you want to explore your dominant side enough to tell him about it? If you do, which it sounds like, you should tell him.
Tell him you've met someone that you think you'd like to be dominant with, while your husband watches, that you think would be receptive to the idea.
If he sounds interested, or willing to consider, there ya go. That's the first step. If not, then at least you'll both know how you feel.
If you go ahead with it, and don't tell your husband (which will seem more tempting the longer you don't talk about it), you've got an affair and all the terribleness that accompanies it. If you do nothing at all you may feel unsatisfied. You need to make yourself vulnerable, and ask him a question. He can't hold a grudge, or think differently of you over a question.