Upvote:6
Under INA 222(g) (8 USC 1202(g)), if you used a nonimmigrant visa to enter the US, that visa is automatically void when you stayed beyond the date on your I-94, for any amount of time. Furthermore, you can only apply for US visas from your country of nationality from now on (although you might be able to apply in your country of residence under "extraordinary circumstances"). These consequences are required by statute ("shall") and are not up to the discretion of an officer. See 9 FAM 302.1-9 in the Foreign Affairs Manual for more details.
Upvote:8
Legally, it is your responsibility to leave enough buffer so you make it in time. Therefore, it is an overstay.
At the end, it depends on the deciding Officer - overstaying 30 mins after a delayed flight and a long line at the border would be a pretty convincing argument to me - but I am not making the decision. There is no way to know for sure until the decision is made.
it might be a good idea to keep some kind of proof, like your boarding pass and a print-out of the delay from the airline's website, to make your point that it was really only 30 minutes (and not 23 hours).
But at the end you are dependent on the officer's decision