Hello Rick,

Thanks for your question.

No, I do not think you got toxic compost. I think you had two other issues:

Topdressing in the fall is tricky. If you cover grass plants with too thick of a layer of compost or soil, when the grass plant is no longer actively growing, the blades cannot emerge above the soil and the crown can get smothered and excluded from light, resulting in death. In the fall, you need to make sure the grass is still growing. It is much safer to top dress in the spring when the grass plants are aggressively growing and they are less likely to be smothered. You still need to be careful to not apply too thick a layer of soil. https://s3.wp.wsu.edu/uploads/sites/2079/2014/02/TopDressing.pdf

Second, about the deepest grass seed should be planted is a quarter of an inch. The seed should be applied on top of the top dressing, lighted raked in and then rolled to maintain good contact between the seed and the soil. https://turf.cals.cornell.edu/lawn/lawn-care-the-easiest-steps-to-an-attractive-environmental-asset/starting-fresh/plant/

So, yes, you can reseed over your compost. Here is an article about spring lawn seeding: https://www.canr.msu.edu/resources/establishing_a_new_lawn_using_seed_e2910#:~:text=Spring%20is%20the%20second%20best,topsoil%20moist%20without%20creating%20puddles.

Hope this helps.