You may be right. Oddly, I don't remember despite having just watched the film again and looking out for that particular scene. Missed the tree for the woods. It was a prominent line of dialogue in Laura's secret diary.
I do wonder if it was Engels or Lynch lifting material from Jennifer's Secret Diary for FWWM. He claimed to have not read it but iirc one of the Log Lady intros pretty much lifted a quote from the book and he definitely wrote those intros himself. He also wrote the forward to the reprint in 2014.
Sometimes I wonder if he also read Frost's two recent books and was just being cheeky/making a point in claiming he hadn't.