Antenna matching network. What? Why? How?
Honestly, you're probably OK. The trace length is short enough that it's really not too significant, the important part is the balun and transceiver IC output impedance, which is probably only somewhat close to 100 Ohms differential. You may lose some range, but the fact that you're using a chip antenna is probably more significant. 

Putting footprints in to play with the match might help, but it might also open up a big can of worms as well.