No se te pasó

[AngelicaDeAlquezar]

I've been thinking about this and this is the best explanation I can come up with. If you keep asking questions, I'll study a little more.

Escrito originalmente por Tyrn

With ocurrir vs ocurrirse it's another story because ocurrir and ocurrirse are essentially two different words? Makes obvious sense, kinda.

I wouldn't say they're two different words. As Wrholt said, this is a case where "se" is used to talk about an "accidental" action. The idea happened spontaneously in your mind, not in your whole body, if you will.
Although you might find things like "me ocurre pensar que..." instead of "se me ocurre pensar que..." in literature, the common usage of the verb to make a difference of both meanings is well established in the dictionary.

Escrito originalmente por Tyrn

Mind you, I have no trouble understanding all the sentences, it's intuitive enough. I can't yet catch where the subtle difference is. Is it that pasar and pasarse have the same meaning and you just don't need se?

In this example of "pasar", "se" is most probably influenced by how we use "ocurrírsele algo a alguien", where this idea passing through someone's head is an accidental/spontaneous event.