Storing the lens in the refrigerator for a month or even indefinitely at 43° will not harm it in any way. What could potentially damage it is removing it from that environment without taking adequate precautions.

Any time you move your camera or lens from a cold environment, such as your refrigerator, to a warmer one you should be sure to place it in a container of some kind so that the temperature change is gradual enough that moisture in the warmer air does not condense on or, more importantly, inside the lens. This can be as simple as a zip lock bag or a camera case or the backpack it was stored in when it was in the refrigerator. If you do have moisture condense inside the lens it will usually leave water spots behind. Moisture can also promote the formation of fungus inside the lens. If the moisture is extensive enough, it can even cause havoc with the electronics of the lens.

This question and the answers submitted cover how to prevent condensation when going from cold air to moist hot air: What precautions should I take when taking a camera into humid conditions?

After the fact, you need to dry it out as best you can. See How do I dry water condensation off my camera?