flashback
An involuntary recurrence of some aspect of a hallucinatory experience or perceptual distortion occurring some time after taking the hallucinogen that produced the original effect and without subsequent ingestion of the substance. (ref. online medical dictionary)

flashbacks (feeling as if you are actually in the traumatic situation again). AllPsych Online.

I think what you are looking at are good memories, as flashbacks are considered negative, sometimes inaccurate, recurrence of an event.