I think they mean it went through a long period of time of not being popular-- it wasn't in the top 1000 for nearly 50 years before Bewitched, when it suddenly jumped to the 400s and grew from there.
And like Lakin said, Katniss is just another flower name. An uncommon one, but it's not made up, not like Khaleesi.
My PNL = http://www.behindthename.com/pnl/37275
Top: Henry & Lara (main) / Caspian & Briar (GP) / Leon & Georgiana (top25)
Bottom: Trajan & Jacoba (main) / Dinadan & Melpomene (GP) / Corvo & Ourania (top25)