Probably not typical, but it won’t bother the plant. It may start blooming next warm spell. I would not cover it with anything since the heat trapped by a jar in sunlight vs at night would be a large temperature swing and that might cause damage. Since you are near one of the Great Lakes, that will mitigate temperature extremes unless the Lakes freeze which seems unlikely given the warmth of this winter thus far.

Primroses do fine here on the border of z4 and 5, so yours shouldn’t have issues.