The Washington Post’s explanation for this is the same as my own: the longer people go without seeing him, the less intensely they dislike him. The more you see him, the more you remember what a catastrophic dolt he was. Were we to have to cringe through more of his press conferences, those numbers would go right back down again.
Also, there are plenty of Tea Partiers who probably kind of like him, partly because he isn’t Obama. I follow someone on Twitter who spent the entire election cycle counting down the days until the principles of the Founding Fathers were restored. She was referring to the the hoped-for election of Mitt Romney. That, in her mind, would bring back Thomas Jefferson. There are a lot of confused people like her.