Time travel and interlibrary loan

The following argument is valid. I don't vouch for soundness!

1. (Premise) If I ought to A, then I can A.
2. (Premise) If I have received an interlibrary loan item, I ought to return it on or before its due date.
3. (Premise) If I can return an item on a date before today's date, then time travel is possible.
4. (Premise) Today I have received an interlibrary loan item due on March 8, 2011.
5. So, I ought to return an item on or before March 8, 2011.
6. So, I can return an item on or before March 8, 2011.
7. (Premise) Any date on or before March 8, 2011 is before today's date.
8. So, time travel is possible.

Premises (3), (4) and (7) appear to be true.