That is interesting. Perhaps there is a common solar phenomenon that explains this.
Both Earth and Mars indicate this by melting ice caps. The analogous phenomenon may be what is increasing Pluto's atmosphere.
This phenomenon, whatever it's cause, has been estimated to cause the complete melting of the CO2 cover over Mars southern ice cap over time scales of only a few hundred years.
But why would it only stop there? Perhaps this "warming" (more precisely we only know the Mars southern cap is melting) would continue so that also the underlying water ice would sublimate or melt. Note for increased sublimation of the water ice the temperature would not have to reach 0 C.
In that case water is an even better greenhouse gas than CO2. A partially sublimated southern water ice cap may allowed sufficient temperatures and pressures to allow open water pools on Mars. We may have observed even liquid water precipitation in that case.
We would expect also such precipitation to cause increased erosion of the surface and to wash away sedimentary covers of subsurface carbonate that has been proposed to be widespread on Mars:

Pathfinder found red, white and blue rocks on Mars.
"A University of Arizona scientist told the American Astronomical
Society that Pathfinder pictures taken with different filters show a
faint bluish tint on one side of exposed rocks, while the other side
of the rocks is a typical Martian red. Some partially buried rocks
are a whitish color and may actually be layers of a hard material
called caliche, a calcium carbonate rock material common in Arizona."
http://www.spacetoday.org/SolSys/Mars/MarsPathfinder.html

This exposed carbonate would be expected to decompose under an aqueous environment releasing more CO2 to the atmosphere and thereby increasing the greenhouse effect.

Bob Clark