It's the kind of thing I might do but I'd freaking TELL you, and in time so that you know how to handle the rest of the interview.

I don't think it's wrong to have a test that exceeds the range of the tested. Really no one should ever ace any test, else the test is insufficient. Thermometers don't just go up to room temp. So a sneaky question that only a truly insightful and thorough person might get, and ballsy enough to challenge the interviewer, and with good enough judgement to know when it's right to talk back, that I myself might not get, is fine. But it's there to identify the exceptional, to provide room in the plot for the spikes instead of clipping, not to kill everyone else.

I sometimes give people way too much credit though. I bet it was all face value.