I really couldn't say for sure, but I do know that all the toes share two ligaments that hold them in place, in relation to one another. That's why, when you have a bunion, the big toe starts to move; the bunion is pulling the toe one way, but the ligaments are pulling it another direction. So, I'm assuming that when you're pulling on the big toe, the others might be affected by the shared connections.
Please remember that I'm posting as a total layperson and that I could be completely wrong!
But that is pretty much how my doc explained it to me.