The drain running down the pillar should be enclosed. I wouldn't think the smell would be coming from the middle of the drain.
I wouldn't discount the possibility of the cabin filter needing a change. I noticed mine having a bit of a sour smell the other day. Smells kind of like vinegar.
My wife hadn't said anything, and I'm not in it all that often. I need to change it, but I've got two arms that aren't what they should be right now (new shoulder in one, in a sling, and a PICC line in the other).
My cabin filters always look like new when I change them, but the smell goes away with a new one.