I disagree with the answers saying it is a mistake to ask. I have sat on both sides of hiring panels, and my experience is that if you have an important question, it is usually much better to ask. Far from showing weakness, it shows confidence. Timid interviewees don't ask questions (perhaps out of fear of appearing weak?), which means that they sometimes don't know how to answer, may answer the wrong question, or even panic as their minds race and come up dry (I've seen it happen). It stunts the conversation and makes them appear less capable. Or, overconfident people also fail to ask questions, making themselves seem closed off to input and unteachable.
Confident (but not overconfident) interviewees ask clarifying questions because they are comfortable in their own skin, and want to give the best answers possible. It starts a more satisfying conversation, and gives good (usually positive) insight.
In fact, at the end of the interview, when they interviewer asks, "so, do you have any questions for us?," I always say, "yes," even if I don't. If nothing more, I just ask, "aside from what we've already talked about, what else can you tell me about the company / job / team / [whatever]?" And then I listen attentively and say it all sounds great. It builds a positive connection, makes you stand out, and gives them a chance to talk about something that's important to them. Also, it reveals things about the company you're considering working for.
Your question is a good one. I would ask.