Great podcast episode this week!
While I agree with Chris and Jake about being nervous about where the Sarah Palmer storyline could potentially be headed, I also think it is important to cite previous examples of her being aware on some level of some of the stuff going on in town.
In the first season, she and Cooper are the only ones able to see Bob. And it is her vision that provides the police sketch for the wanted poster, so she seems to be able to tap into that world fairly early on. I also believe it is in Laura's diary (??) that she confirms that her mom has strange feelings/connections to the woods too. Or just strange visions. There also might be mention of it in the show as well, maybe Donna says it to Maddie or James. And then of course you have the season 2 finale, where she is possessed by Windom Earle.
In terms of her current day "possession", it is my hope that they will not try to retcon it as being something that has always been there. However, I can totally see this particular instance being a recent development, and can personally buy that it is happening at all because of the past examples of her being connected to the Lodge world in some way. Since the pilot episode, Sarah Palmer has been a fascinating character, and Grace Zabriskie knocks it out of the park every single time.