Because it seems to happen as a consequence for the movement, and it’s consistent. My hydration levels aren’t. Regardless of how much or what I’ve been drinking, of how much I’ve been sweating, I still feel it. Also note I don’t feel it as much after doing an intense workout in which I sweat bullets. And I’ve never felt it if I’ve been resting the whole day even though I’m sure I must have been dehydrated occasionally on rest days. Also it feels more like something on the skin and not like a regular muscle spasm.
That’s just why I don’t believe it is dehydration, but you could be right, it could be dehydration.🤷🏼♀️