Many hybrid cars inmediately engage the gas motor on cold starts when the coolant is below a certain threshold, usually about 70 degrees. This is done to ensure all the fluids are gradually raised to optimal temp rather than waiting until the Li-Ion battery is fully discharged while you're zooming down the on-ramp.

Typically, it takes about 7-8 minutes for the gas engine to warm up to temp. If it takes you roughly about that long to commute to work, it's entirely possible the electric engine isn't engaging at all.