Olives are one of my favourite low carb foods, as they are also low in protein. I am often buying the Lidl Eridanous olives stuffed with dried tomato, in olive oil (claims 0.1g carbs / 100g drained). I normally place the glass into the fridge, and then the oil gets cloudy and develops little solid bits. With the last glass this has not happened. Is there a problem with the oil, or can it just be a slightly different batch?
"Olive oil will harden at refrigerator temperatures -- around 37 degrees F. Water is a pure substance, so it freezes at an exact temperature. Olive oil is a complex mixture of oils and waxes. The heavier oils and waxes will form needle-like crystals as the temperature is lowered, then the other oils will start to settle out. Winterization is the commercial process whereby these waxes are removed to keep the oil clearer when stored on a cold shelf. It is used mostly for aesthetics and to improve mixing when combined into mayonnaise, sauces, and dressings.
Because olive oil is a natural product and different from year to year even from the same bottler, each batch of oil will "freeze" at a different temperature. There is no exact freezing temperature. Freezing olive oil will not harm it; it will actually prolong its nutritional benefits and its flavor. It is a myth that the freezing point of olive oil can be used to predict whether it is pure, virgin or extra virgin."
Source: http://www.oliveoilsource.com/definition/freezing-point-olive-oil
Some olive oil does (try to!) solidify in the fridge, so it's probably nothing to be concerned over. As far as I can remember it's the virgin olive oils that do this, but since olives can be grown under different conditions, it's quite possible - particularly if you got your jar from a new batch - that the purity of the oils is slightly different and so you're just seeing a slight change in its reaction to a cold environment.
Robbity
PS I see @Dark Horse has just beaten me to it, and has given you a somewhat more technical explanation!