Ah yes good point sorry should have said ...Clean oil off discs with a rag afterwards even wash them in detergent.
But also, (For modern ish motorbikes, don't know about push bikes) ...even if you forgot, those discs and brakes are designed to work just fine whilst getting covered in oil and dirt, like London roads for instance.... Id imagine they could mostly still cope even being completely immersed in oil.
But yes clean it off.