When designing PCBs with RF functionality it is considered good practice to place pads for a matching network immediately before the antenna (or antenna connector). This allows you to compensate for any impedance mismatch arising from design and/or manufacturing issues in the PCB:
A different rule of thumb is that you don't have to worry about RF propagation complexities if your trace is shorter than 10% of the highest frequency component wavelength.
Does this imply that I can omit the matching network if the feed line is very short, electrically speaking?
For example, would the following layout be OK? This is for 915 MHz, with 2mm between the antenna and the edge of the ground plane. The IC is a filter/balun from Johanson Technology. (The 2mm distance was dictated by the antenna datasheet).
(The design isn't completed; I still need to add stitching vias, pull the ground back from the differential microstrip, etc.)