Ive noticed that sometimes when I smoke Herb, I have the urge to grind my teeth like Im on coke or something. I know the Herb isnt laced though, because its from my own stash, grown from my own plants. Unless you start to hallucinate (Im talking full on hallucinations, not CEVs) then the herb probably isnt laced.
It was probably just some real potent Herb. Buy more of it if anything!