What is actually a "mouse problem" (Missouri, FYI)?

[Jessica Murray]

My tenant, who lives in the unit above me, complained of mice earlier this month. When I had the pest control guy over, he could see no signs of an "infestation" and explained to her that in old houses it's common for there to be a mouse or two. She refused the offer of snap traps and glue traps, and only allowed him to put out one poison box. 

I live in the downstairs unit, and while I've noticed a mouse or two, I put poison and glue traps before the pest control guy even came (I basically had him come to appease her and legally cover my arse). The glue traps in MY unit so far have not caught anything, and I occasionally smell a dead mouse, and occasionally hear one. In my opinion, this is just a normal winter and the poison has kept the mice under control.

I'm not sure what to do about my tenant. I want to keep this from escalating. Her lease states that after the first 30 days, she was responsible for dealing with pests (although I think that MO law requires the landlord to keep the building "habitable" http://www.ncsl.org/research/environment-and-natur... ). 

Do I buy her some d-con and glue traps and tell her to put them out in her apartment? Do waste money and have the pest control guy come out again? Do I remind her that a few weeks ago she refused, in front of me and the pest control guy, to use snap and glue traps and only allowed him to put out one poison bait station?