The seasons -- a theory

Back in Season 2, when Pycelle says that Autumn has come, he says it's because all the Maesters met and simply decided it was. But nothing ever is really shown to suggest that it's Autumn. No trees ever change color or lose their leaves (Sam says they do, but we never see this), and even though Marjory talks about bringing food to Kings Landing, no small folk are ever seen out in the fields bringing in a harvest. And with the exception of the North, the weather never really seems to get much colder (judging by how the people in Braavos or the Riverlands dress).

So perhaps the way the Maesters determine the seasons have nothing to do with where the planet is in relation to the sun and just goes by the average overall temperatures of the continents. GRRM has implied that the reason the seasons are all mixed up has to do with the presence of the White Walkers. But if one pauses to think about this scientifically (work with me. There can be science in a fantasy world), it doesn't make sense. Seasons are caused by extraterrestrial forces, not by the presence or absence of a terrestrial being.

SO, just maybe, Westeros has been having regular solar seasons all along, but the presence of the White Walkers, along with the Doom of Valyria, had conflated the temperatures to the point that people stopped looking at the sun anymore to figure them out. This would then help explain why there was that false spring, or why we only ever see one sun, even though unpredictable seasons are often caused by a planet in a binary star system.