 In particular, when adding a new travel signature to the OPT, it is the responsibility of the international student office to make sure that the student is still enrolled at the institution.In case the Form I-20 runs out of space for travel signatures, the international office may print out a new Form I-20 for the student.In the special case of automatic visa revalidation, whereby the student returns to the United States after a trip to Canada, Mexico, or a nearby island for at most 30 days, it is not necessary to have a valid visa at the time of re-entry.