I got a reply from Lucy Zhang of KXL, very gracious.  They have no official market maker.

Which makes the business of repetitive-like-clockwork trades of 100, 200, 300 shares on slow days more interesting to me.

Anyone have experience with this?  Is that really collusion in trading?  Probably illegal, probably common.

I'd love to know.  I know a couple of professional traders - I'll try to remember to ask them.  Anyone else?