The idiom in one ear and out the other is used to describe something that is essentially ignored or dismissed after being heard which is what being stated in this context by saying that it didn't go in one ear and out the other a.k.a it wasn't ignored or forgotten.
Context: "It wasn't glib or run of the mill ,it wasn't ignored or forgotten immediately after being heard." Claim: "It wasn't glib or run of the mill ,it didn't go in one ear and out the other."
Considering the context, is the claim true, false, or unknown?