Taurus apparently had a batch of 85's that would light-strike (this was 3 to 5 years ago). When I first picked up my 85 Ultra light (after owning 2 stainless 85's), I had a problem with misfires. I sent the gun back to the factory (through the dealer) for repairs. Never had any problem with the stainless guns. And, no problem with the 85 Ultra Light since either. It's my primary carry piece.
In your earlier post, you mention this gun doesn't have the integral trigger lock mechanism and had Uncle Mike grips. You questioned if the gun may have been used. I suspect it was a used gun....or, if new, it's been setting around for almost 5 years (or more).
I suggest you send the gun back to the factory for the misfire situation and run 200 or mores rounds through it ASAP when it gets back.
As far as being new or used? Well, Taurus warrants the gun for life or the gun, regardless of the owner (this doesn't apply to the aluminum framed guns, by the way). And, if you got as good a deal as you say you did...I wouldn't worry about it.
I assume you did buy the revolver from a dealer, correct?