I-94 Expired

 This is probably a human error on the part of the CBP (Customs and Border Protection) officer.  Your Admit Until Date should have stated D/S (duration of status) instead of a specific date. Could you please check your passport to see whether the CBP officer wrote D/S on the admission stamp in your passport? When you arrived in the US, did you have your DS-2019 with you that you presented to the CBP officer along with your passport? 

If you did have your DS-2019 with you upon your entry to the US, the next step would be to contact the Deferred Inspection site.  You will need to let them know your I-94 has an error on it and find out what you need to do to get this corrected.  Below is the information for the Deferred Inspection site in San Francisco: (Find closest site here and include that information below: https://www.cbp.gov/contact/ports/deferred-inspection-sites) 

San Francisco, California  

U.S. Customs and Border Protection  

630 Sansome St. Room 1185  

San Francisco, CA 94111-2280  

Hours: 7:45 a.m. - 3:00 p.m. Monday -Thursday  

Phone Number: (415) 844-5227 (415) 844-5228  

FAX: (415) 844-5235 

Please call the number listed between 7:45am-3pm on Mon-Thursday and speak with the agent.  Once you explain to them the issue, please ask if you can fax them a copy of your passport, passport stamp page and DS-2019 for them to fix their record.  Sometimes, they are able to do this without you having to report to the CBP office.  However, more often than not, they would require that you report to the CBP office and present all the paperwork in person.