That's a bug with the ping calculation at the end of the map and/or scoreboard. It shows the ping steadily increasing but your ping isn't actually doing that.
Ah, yeah. I know that's one of the things on Epic's enormous todo list. Joe Wilcox mentioned a few times that their goal with the HUD is to make everything modular and easily configurable. After I finish some other stuff I'm working on I'm going to start helping out a lot with stuff like this.