The irregular orbit of Pluto causes seasons. The fact that it is heating up as it moves away from the Sun is no more surprising than the fact that temperatures in the Northern Hemisphere tend to be colder in January than in December.
But what's this about Mars heating up?
I kid you not: they have discovered that berylium isotopes correlate to various global climate conditions. They've found that higher concentrations of berylium isotopes correspond to higher global atmospheric temperatures. They've ascertained that berylium isotopes are created through interaction of the atmosphere with solar wind particles. They've found that higher periods of solar activity correspond to higher levels of berylium isotopes.
What's really really puzzling the scientists: they believe that there appears to be some sort of influence of the earth's climate by the sun. What this influence is is not entirely clear and more research needs to be done to pin this baffling issue down.
If you actually read the research paper that broke that revelation: you'd want to grab a stick and beat them over the head while screaming, "DOES UTTERING THE WORDS A HOTTER SUN HAS A SIGNIFICANT INFLUENCE IN WARMING UP THE EARTH'S GLOBAL CLIMATE CAUSE YOU THAT MUCH PAIN? WELL DOES IT???? DOES IT???? HOW DOES THIS FEEL???? FEEL BETTER NOW? WHAT ABOUT NOW? Seriously, I'd feel seriously better after beating them silly with an ugly stick. For sure, but that's just me.