To optimize meter sensitivity over the widest range, the Pocket Spot Light Meter subranges in two places: at the low end and the high end. For various reasons, the high end sub-ranging is not an issue and will probably never be noticed. But because we photographers are so interested in the shadows, there are times when the EV 5 to 6 range is very important. It is in this range that the meter sub-ranges, i.e. it changes from 1 degree to 3 degrees to gather more light.
So, what happens if the one degree shadow is surrounded by something slightly brighter and the meter sub-ranges? If it isn't that much brighter, the meter will meter the 3 degrees and that is that, but if it is several stops brighter, it will go between 1 degree and 3 degrees displaying a reading that oscillates between the brightness of the 1 degree and the 3 degree. This can be confusing, but knowing what the meter is doing can clarify the reading.