The fast food chain is testing the change in 14 locations in the Dallas area since November, according to NRN. Apparently, the burger patties are also cooked to order rather than kept in a warmer.
The test is limited to the chain's quarter-pound (4-oz) patties. The 1.6-oz beef patties for their regular hamburgers and Big Macs are not affected by the test (which I suppose makes sense as a fresh beef version of their thin patties might just fall apart on the grill).
Photo via McDonald's.