Has anyone else ever had an olfactory hallucination? (aka smell something that is not there)

[NightWatcher]

I'm just sitting here listening to tunes on shuffle and St. Stephen by the Dead came on after a Radiohead song and for nearly a minute I would have sworn that I smelled marijuana. I went outside to see if the old man who lives next door was using "glaucoma medicine", but there was no sign or smell of weed.

Has anyone else ever smelled something that was not there? The halluci-smell was brought on by the Grateful Dead tune.