iPhone randomly changes timezone in Mexico

My iPhone changed time zones the night before I was supposed to catch a flight out of Chihuahua back home to San Diego. My alarm went off as scheduled on the phone, but it was an hour late and moments later my app was telling me the flight was boarding. Obviously I missed it. I turned my phone off and back on and it corrected itself to the right time. When I was at the airport negotiating my way onto the later flight the gate agent told me it happens a lot with iPhones is this true? It is something being done about it? Or do I just need to remember to turn off automatic time adjustment while in Mexico?