should this be plugged?

[44BZ]

This is the passenger side where the hood meets the cab. You can see just below that rubber grommet and to the left what looks like a small flap. It's caulking and behind that is a small slit that goes into the fresh air vent. That slit was not plugged on the driver side so I'm wonder which is right. Plugged or unplugged?

[bruner1981jpce]

Seems to me like a place where water can seep in and sit, and that can't be good any time. I'd say if you can't find any legitimate reason for it to be open, I say plug it.