Overall it doesn’t hurt, most of us have a few of those… If someone doesn’t have a 1 or 2 star rating, in my mind they haven’t done enough. Since you have 200+ reviews, a non-issue for you overall. (You still have a 5 star rating even after that review.)
I agree with @photoswatch. I rate them 5 stars even if they were a pain and/or rated me 1 or 2 stars. (I only have 1 star and 5 stars… someday that 2 star will arrive. )
THEN I explain what why they rated me low. Something like:
“Client requested additional work beyond the original gig, then rated me low because I wouldn’t do it free. A very nice buyer until I wouldn’t do the extra work for free.”
People see you are being reasonable, and not petty.
I respectfully disagree with @divideszero. I do NOT rate them low with the stars. I also make sure my response is professional and factual. Even if the buyer was rude, I do NOT respond in kind. Maybe in my mind I’d like to slap them, but it doesn’t help me or my future clients, so I simply let it go.
For perspective: I had 2500+ gigs without any 1 star ratings. Then I’ve had three or four in the last eight weeks. All were for the same reasons: I wouldn’t do free extra revisions for things where they changed their mind AFTER I delivered.
Worse, while I do a crazy number of $30-$200 gigs, all of my 1 star ratings were on $5 gigs except one at $10. Meaning the clients who purchased the smallest amounts. One guy even used my voice for his primary gig videos… then later claimed my quality was poor before giving me the bad review. (He simply wanted free work.)
It just goes with the territory of growing on Fiverr. Stand your ground and stay professional, non-emotional in your responses.
(I run it by my husband, and/or often sit on my response for a few hours or overnight to make sure I don’t say something over the top. I may write it, then copy it out to a scratch pad and wait a few hours before sending.)