Just read the whole scene aloud with "slithered" and laughed for a good three minutes. Ah, I needed that, though it's really not the reaction I'm hoping to inspire in readers. Needless to say, the word is back to "slid."
It's funny because beginners often obsess endlessly over word choice on their first drafts, the result of which being that they're married to what should probably be disposable text and so focused on the trees that they can't see forest to save their lives (or manuscripts).
But at the polishing level of one's revision a small word choice issue can have huge impact.
"Slithered."
So help me....
Bahahahahaha.