
Quoting
Mr. Knowitall
Your thirty days would have started running at the end of your program. But the small discrepancy might not have been detected. This is more of an issue if you're from a country that participates in the visa waiver program, as if you enter under VWP you won't find out until you're at a port of entry. But if you're from a nation where you have to apply for a tourist visa, if you get the visa you can be pretty comfortable that they were satisfied with your departure date based upon your I-94.