That was supposed to be remembering? I thought that Oak put some spying device on you and just told you that every time you'd try to use something when you couldn't.
Later games/remakes changed it to something like "Oak's voice echoes in your thoughts" instead of just "OAK:". Although I suppose he could be psychically invading your mind, which explains how he knows about your illicit biking.
But yeah, I would love for it to turn out that there was some spying device on you, and a holographic projection of the professor pops out of nowhere.
Socran's Razor: "Never attribute to massive stupidity by someone else, what could be explained by a tiny bit of stupidity on your own part."