You can never be too safe. I would try Plan B, it can definitely still be effective for up to five days. Also, don't freak out if the hormones from Plan B mess with your cycle-- you may miss a period or have heavy bleeding. It sometimes takes even 3 months for your cycle to get back to normal.
Just take the morning after pill as an extra precaution because, like I said, its never a bad thing to be too safe.