Sorry Anebel, I don't know where you are or what your definition of Northern is. I'm in Western Washington and that's Northern to me, but then you might be referring to Alberta, Canada and that's a lot colder Northern.
The problem with the fungus is that the disease is most concentrated in the seed head. The infection started out way back in the '40s but no one knew about it until the mid '70s and by then it was all over the place. The reason it's a bigger concern for southern climates like the OP's is because the infected strains have a better survival rate there so it's pretty well dug in, harder and more expensive to replace with non infected strains. All that said, it leaves us with about 40 years of a very popular grass seed making it's way all over the place.
I guess the only way to know for certain if there is a concern is to have your grass analyzed.
I hope that helped a little.