Single Responsibility Principle states that every class or module should have one reason to change. To restate it for clarity. A module should be responsible to one, and only one, actor.
I disagree with this statement, i.e. I don't think it's a good rule to follow. And I know Uncle Bob says something very similar or even the same, still.
Let's just think about this a little. Say I have a simple Amount class that has add() and subtract(). What if one "actor" only needs add() and another subtract(). Should I split this class? Would that make the code more maintainable? I don't think you would argue that it would.
Before you say it all depends and you should always exercise judgement, I don't think a rule is a good rule when it doesn't even apply in simple cases.