Very little air out of the heater blower in the dash.
 

I just noticed this morning, even on full speed there is very little air actually coming out of the air vents. The fan (sounds like) it is working as normal but as if the air is leaking somewhere behind the dash.

I cycled all the vent options and it's the same everywhere, just very little air coming out.

Are there any common places where an air leak can develop?

I had a similar problem on one of my other cars. I would hear the fan kick on full blast and feel a little bit of air coming through. Turns out the cabin air filter was due for a replacement. Maybe just remove it quick and see if you get air flow.