NASA's Curiosity vehicle has measured the highest concentration of methane ever through the SAM laser spectrometer: 21 ppbv. Curiosity has frequently detected methane, based on these measures it seems that the concentration increases and decreases by seasons. Occasionally you have also measured abnormal concentrations, but still do not know how long they last and whether they are intermittent or exceptions.
Again, they don't have any more data to know if it's something extraordinary, or why. This last question is key, as methane can be produced by living beings, but also by reactions between rocks and water.
NASA has announced that it takes longer to collect more data and properly analyze all measurements. In addition, it is intended to analyze the data of the ESA TGO probe (Trace Gas Orbiter), which hope that the combination of measurements collected on the surface and orbit of Mars will allow them to know the source of methane and its evolution in the atmosphere.