Certainly not intentionally!
Well I'm pretty familiar with these failure modes. "Mixing" and "intermodulation" are pretty synonymous, the former is used for the intentional and the latter for the unintentional effect creating the intermodulation products (aka "images"), usually due to overloading. There was no strong signal within the frontend bandpass (the 'OVL' indicater would have come on), hence there was no overloading and the radio is a direct-sampling receiver, meaning it does not have an IF to create these images either.
But anyway, I checked my records and I happen to have recorded the output of the KiwiSDR, which was not 30km up north but 120km SW in the inland:
This was recorded few minutes after I shot the video, off a very different radio 120km away, with an obviously much weaker signal. I don't think there is any better way to prove that this did not happen in my radio, which I used to check WWV at that early hour fairly often and got to know pretty well by now. But I obviously anticipated this discussion, that's why I recorded the RF gain reduction (which would have killed any internal distortion on this particular radio) and recorded the KiwiSDR.
1kW from ~4,300km away, that's pretty awesome! My "best kilowatt" so far was 1650 KCNZ in Cedar Falls, IA (6,700km)