I think I “see” what’s happening. Just now I had my monitor color corrections set in such a way that certain visual attributes were emphasized. My eyes happened to focus on the right end of curve #10001 the moment its cursor changed direction at the left end of that curve. At that moment, and for only a couple milliseconds, the shape of a cursor appeared at the right end of the line (while it was apparently at the left end changing its direction).
So, here’s my speculation: At end end of its travel, the cursor makes a high-velocity sweep all the way to the other end (it must also reverse at high velocity, but those triggers only generate a single OSC during the retrace, so perhaps the return sweep occurs before the triggers can reset).
I (sort of) “proved” my theory by nudging one of the offending triggers out of reach of the cursor’s path and, indeed, that one did not trigger during the retrace.
Conclusion (speculative, of course): There exist cursor re-scans (maybe call them retrace, after raster-scan technology) that are so fast they’re invisible, and they re-fire any triggers in their path.
In the attached score, triggers #172 and #173 fire when cursor #1 reverses direction at the end of its curve (when that cursor is nowhere near those triggers). They do also fire at the correct time (when cursor #1 strikes them).