The only way condensation could occur inside the mini is if the inside of the mini is colder than the air going into it. Condensation happens on cold surfaces that cool air down so the air can hold less water. At a given humidity, the temperature at which condensation occurs is known as the dew point. When running, the mini will always be hotter than the ambient environment, since it is dissipating power. Because it's hotter, any air that goes into the mini will get heated up, and will become less humid than when it went into the mini (the same amount of water will be held in the air, but since the air is hotter it has more total water capacity so this relative humidity is lower).
Condensation on a hot surface is physically impossible. The only way there could be vapor-based condensation in the mini is if (as someone previously suggested) a hot beverage was steaming supersaturated air directly into the mini's air intake. In this case, the mini may be colder than the steam, so condensation could form inside.