Totally normal, especially if slurry was taken from a pot full of fresh FFOF. Have heard countless people complain of it being too hot for seedlings and people mixing with more Perlite, coco coir, FFHF and sand to offset strength.
I personally have gotten much higher slurry tests(4400ppm) but years of using Fox Farms potting soils only(I use Strawberry Fields-less nutes/more aeration) I have found that mixing crushed eggshell, wood ash, and amendments like Jobes dry Tomatoe fertilizer, Dr. Earths Tree and nut dry stuff and like like work well in combo and will release notes in more uniform fashion, throughout the grow, to where you get 1250ppm slurries until flush.
Yeah, craft grows are the best...the info people who do for non-profit grows is substantial, you sure wouldn't get info like this from a commercial grower. Had to put that in there as I see you've posted ads on my page and then removed your name...
Hope that helps.