Hybrids are more accurately named "charge sustaining electric vehicles." They will try to maintain the State of Charge in the battery within a small range - in my Accord in ECON mode it is between three and five bars. I assume the CR-V is the same, or at least similar.
When you first turn the car on, it will start the engine to charge the battery if the SoC is below this range, or if the computer thinks there is a reason it will drop below it due to background electrical use. It can also happen if the battery isn't capable of supplying enough power alone, regardless of SoC. The biggest culprit is the automatic climate control. If it bothers you, try turning ACC off before you park the car.
