If I'm doing the math right, it is one IR pulse lasting 10 microseconds.

I can think of lots of things that might do that, but no one possibility that stands out.

I don't know enough about photography to know where that would use electronic flashes that fast, but I assume there is some use.

Bad enough batteries in an ordinary remote could do that. But I don't think you'd post that as "try to guess".

I think that's the right time scale for a spark of static electricity. But I think you'd be more careful with your Pronto than to try that.