I really don't think it'll be a big deal... I have had the same problem, and as long as what I write was well-received and I was only like, a minute late, they are really quite forgiving of our tardiness. (and OMG I just realized that "Tardis" and "tardy" are from the same root word, holy shit linguistic mind fuck!)

I think at the worst they'll just wait till the next amnesty week and add you to that list!