Is my metabolism really revved up postexercise?

Yes it is and it’s due to Excess Postexercise Oxygen Consumption (EPOC) which requires extra kilocalories for lactate removal, glycogen re-synthesis, creatine phosphate replenishment, and recovery of your HR, hormone levels, temperature, and ventilation following a bout of exercise. You can expect to burn an additional 65-150 kilocalories for 1-2 hours postexercise depending on your body weight. And workouts of greater intensity and longer duration show higher EPOC values and calorie burn. The time of day you exercise has no bearing on the postexercise calorie burn.

Just another reason to keep on exercising!