1) The episode doesn't contain "Q" in the title.
Neither did "Encounter at Farpoint," "All Good Things...," or "Death Wish." Only 2/3 of the episodes featuring Q had "Q" in the title.
2) No one but Picard saw Q.
The same goes for "All Good Things...".
3) I don't recall Q ever mentioning the events of the episode in his later appearances.
The same goes for "True Q" and "All Good Things...".
The most you can legitimately say about "Tapestry" from these points is that it might not have really happened. It can't be conclusively proven that it did, but neither can it be conclusively proven that it didn't. Absence of evidence is not evidence of absence.
 
				 
 
		 
 
		 The old you can't prove a negative.  Picard is uncertain as to whether or not it was truly Q and the audience is left uncertain.  This ambiguity is one of the things that makes this episode so wonderful.   The other thing I love about this episode is that like the TOS episode "The Enemy Within" did with Kirk's character, "Tapestry" does a beautiful job of showing that it takes both the erudite and well as the "Hell bent for leather" ensign who was stabbed through the heart in a barroom brawl facets to make Picard the flagship captain.
  The old you can't prove a negative.  Picard is uncertain as to whether or not it was truly Q and the audience is left uncertain.  This ambiguity is one of the things that makes this episode so wonderful.   The other thing I love about this episode is that like the TOS episode "The Enemy Within" did with Kirk's character, "Tapestry" does a beautiful job of showing that it takes both the erudite and well as the "Hell bent for leather" ensign who was stabbed through the heart in a barroom brawl facets to make Picard the flagship captain. 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		