By design, circuit breakers don't always trip the instant the current exceeds the ampere rating. A common design uses a bi-metallic strip (like a mechanical thermostat, or the "blinker bulbs" in old Christmas tree lights) which heats up as current flows through it. Eventually it heats up enough to open the circuit.
A result of this is that a small over-current (say 1A on a 20A circuit) will take a long time to heat up enough to trip, while a large overcurrent (100A for example) will heat and trip very quickly.
Your compressor might be just slightly over the rated current for the breaker. It won't trip immediately, but after 10 seconds heats up enough to cause the breaker to trip, and the circuit to open.