A typical decent quality room humidifier should cut off when the room reaches 45% rh. That said, you should always reseason in the winter. The box has stabilized over the more humid months and the "shock" of home heating, etc. Can really drop the boxes inherant moisture. You could, with a damp sponge, and I mean damp, i.e., well rung out, wipe the mating surfaces and raised lip on both lid and bottom. Do it every day for a week or more. I have had a lot of success with this.
Also, assuming you are dealing with a desk top, another more daring method I figured out years ago for a box-in-box type construction humidor. I.e., there are cedar panels lining the
inside of an outer hardwood or mdf box. VERY carefully, try pulling out the side panels. Now see if the bottom panel is loose. A better quality box should be loose to allow for expansion and contraction. Take some sheets of cedar, like the kind used between layers or on top of cigars, and place those on the bottom, being sure that they are along the edges/corners. When you re-install the side wall cedar panels, you have effectively raised the lip, providing a better contact for the mating surfaces. If the box is veneered solid cedar, with the lip on top, use some genuine beeswax on the mating surfaces. rub it in generously, and see if that is enough to improve the seal. This method will work on the box-in-box type humi too.
