Daylight Savings and iPhone alarm delay

It is daylight savings and the clocks adjust ahead today. I had my alarm set for 3:30am and when it went off this morning, my phone clearly said 3:30am. Sometime over the next hour, the time adjusted from 4:30am to 5:30am resulting in me missing a flight. Why the delayed time adjustment? I had assumed that my phone’s time had appropriately adjusted to DLS at 2am. Is this typical?