Not really. If you have anything that needs a winter chill in order to germinate I would start it now.

I'm in zone 4b (so only a little bit colder than you) and probably 75% of my seeds have been sown, but only because I was over-eager to get started. Some seeds actually do better if you wait until closer to spring, like tomatoes and marigolds.

Emma

now is a perfect time to winter sow. i've already WS a bunch of stuff: larkspur, poppies, snapdragons, rudbeckia and cleomes.

I just now WS things last weekend, around Feb 17th. I am in a rare zone 6 pocket of a zone 5 world, so I plant assuming I'm zone 5. I believe we will generally have enough cold ahead that I am not worried. I choose to believe that if it says 60 days stratification is needed, they are choosing the longest time period for safety, and it's possible that just 30 or 45 days may be enough. We'll see! But, I wouldn't worry if I were you.