Hi Melissa, your zone 4 would indicate the grass has gone dormant for the year. Best maintenance right now is to rake it to remove all debris. If next season your want to do anything, fertilize Easter, the 4th of July, and Labor Day.

Yes, your grass is dormant now.
As stated taking a stiff garden rake to it in early spring and removing the dead grass (thatch) will be great for it.

Don't worry, it'll be fine.

tammy