How could something appear in my Gmail history if I never saw it?
	
	
		Hello.  I have a question about how the History function on Google Chrome interfaces with Gmail.  
While browsing my web history, I noticed a passage that I know did not come from the text of an email that I ever read or wrote.  When I click on the history listing, it takes me to my Gmail inbox with a yellow message at the top saying "The conversation that you requested no longer exists."  
The passage was offensive and I am wondering why it showed up in my History.  What are all of the possibilities?  Would it be worth having someone look at my computer to determine how this happened.  I would not mind paying someone to do this as the material was very offensive.  
Thank you for your help.