Has this ever happened to you?

Yes, it happened two days ago when I plugged in my new pair of REL T/5Xs and realized I was finally hearing the sound that had been eluding me all these years. I hope the euphoria never wears off, but it probably will.

For me it is more likely to happen when I listen to a particularly good recording. 

I think many audiophiles underestimate 1) the effects of their room acoustics and 2) the quality of a recording in how realistic their system can sound.

I have a Harmonia Mundi (classical music) CD that sounds more realistic than many SACDs and other high-res files I've listened to.  Currently, that is my most-realistic reference recording.

It has happened to me.  And then the drugs wore off.

OK, one more: any time it happens, the owner of the store would wrestle the remote from me and firmly request that I leave the showroom

Congratulations on reaching audiophile nirvana.  Yes it has happened to me several times, but not spontaneously.   Rather it has occurred during evaluating or installing component upgrades when I my analytical persona expresses itself.  After some time, my music lover persona resurfaces and I focus on composition and performance, enjoying the music being produced by my system for years since I do not make system changes often.  I do not have audiophile FOMO disorder (fear of missing out on the latest component loved by the press).  I find I can go from my analytical to music lover personas at will, but 90% of the time, the music lover is expressing itself.