Final answer:
The phrase in question is not an oxymoron as it does not combine contradictory terms; it's more of a paradox representing an internal thought.
Step-by-step explanation:
The phrase "Run away, said the head silently" is not an example of an oxymoron. An oxymoron is a figure of speech that combines two seemingly contradictory terms together for effect, such as 'jumbo shrimp' or 'deafening silence.' However, the given phrase could be an example of an impossibility or a paradox, because heads cannot speak, and certainly not silently. The concept of a head speaking silently suggests a thought or an internal monologue rather than spoken words, which might be the cause of confusion regarding oxymoron.