Nearly Six Months. Do I do Something?

I sent a manuscript out to an agent at the beginning of March. Since then, I've received one e-mail from them, which was a quick question about the manuscript's history. This is a legit agency with credentials, so I'm not worried about anything like that, but I do have another agent waiting to read it who won't read it until this agency finishes, as she reads manuscripts exclusively. Do I send them an e-mail asking if I can expect an answer anytime soon, and if so, how do I word it without sounding, "OMGREPLYNAO." I've been made to wait before, but I feel like this is dragging a bit.