How easy it is for MoS2 to become oxidized I made I high pressurized $\ce{MoS2}$ pellet, using a 6 ton pressurizer. I used very thin powder to create the pellet.

I am using this pellet on beam, with some nuclear techniques. In my spectra I can see oxygen.

How easy it is for $\ce{MoS2}$ to become oxidized?
It seems that the problem has been examined even 50 years ago, probably in order to determine if/how oxidation would alter the the properties of $\ce{MoS2}$ as a lubricant.

Here is an old NASA document from 1949, and in Surface Oxidation of Molybdenum Disulfide from 1955, the authors state in the abstract, that the oxidation is limited to the outmost surface layer, which then passivates and protects the rest of the batch.