from the description the flash was on a separate chip: I would guess most likely a SPI interface. You can absolutely get noise picked up on a SPI interface whic

from the description the flash was on a separate chip: I would guess most likely a SPI interface. You can absolutely get noise picked up on a SPI interface which looks like a command: and if an erase command is 16 bits long, you are going to see that command just with random bits every so often.