Driver side vent emitting hot air even when A/C is off?

Bought my first Prius roughly 6 months ago. 2016 Prius C 1 with currently about 36,000 miles. Now I only really use the windshield defrost when needed and generally don't use the AC/Heater. Just recently I've noticed that when I place my hands near the vent on the driver side with the AC completely off I can feel hot air emitting out of it. Now, it's not in sense blowing hot air as if the ac/heater was on but more so just warm/hot air lingering. It's not audible neither. I have since tested the AC and when on it does work as normal and blows cold air as it should. Should this be a cause for concern or am I over looking it? This is my first Prius and I have been doing it's 5K + 10K (I commute alot) services at the dealer ship on schedule with no real issues to report according to the Mechanic aside from possibly replacing the tires within my next visit (4K miles from now)


Also, on a side note when I first purchase the vehicle it was prompt to kick in on hybrid mode where my MPG would kick off at 99MPG. Now it appears that it takes quite some time for it to kick in, I notice that it takes about 10-15 minutes of driving off the engine for the hybrid mode to work? Should this be expected as the car needs to essentially warm up first? I live in the Bay Area where it is often quite cold in the mornings upon the initial start.

 

Thanks for the input. I did take a look under the hood and everything appeared to be in tact, although I may need to compare to a picture of a similar model. One more note I did run it at idle while the engine was running and did not feel the hot air, only while driving.

 

Thanks guys for the responses, I am reassured by all your input. Correct, AC completely off, although yes I can see how it can attribute to the fact I use the hot air first to clear up the windshield then completely cutting the unit off. I got a lot to learn about this car but thanks, that makes total sense that it can be the warm air circulating through the cabin. I appreciate it!