Well, I'll play a little devil's advocate and send you to
Janet Reid's blog post from today. (Oct 17)
Culling what's pertinent, she paraphrases one of the issues raised in the letter she's answering...
"(2) You assumed that because you could not find any sales in your genre, there weren't any."
...and then responds thus:
"For starters, not all deals are reported. My Publishers Marketplace deal listings are sadly out of date, and not just cause I'm lying around eating bonbons and watching telenovellas. Some deals aren't announced till foreign sales are made. I'm waiting to announce one now cause I want to use the correct title, and I know the publisher is changing it. Never assume you know how many deals an agent has done, or not."
That's obviously contrary to a lot of advice here, and I'd agree, it needs a certain degree of salt. It certainly doesn't mean don't bother to research. But Janet Reid isn't out there to blow smoke up anyone's skirt (or trousers) and she's got a valid point.
Do you know why they want to rep something that seems outside their bailiwick? Did you ask? Are they trying to expand their reach and feel their agents are up to the task? It seems to me it's worth asking. I presume (not having experienced it myself) that an agent understands the professional side of things and wouldn't be offended by such questions. It's an important decision for you and you need all the information you can get, even if you have to ask for it.
If you read the entire blog post, you'll see that Ms. Reid thinks assumptions can sometimes lead you down a bad path. Are you comfortable with them in every other way? If so, gather your gumption and make an inquiry directly to the agent who offered you rep. And best of luck! Hope it all works out.