There are many factors that can affect the polarization this way. We've seen them a lot when the nose level probe sticks and the run valve stays more closed than usual. This can lower the temperature and increase the polarization; this has been covered in the halog before. Any temperature change can cause an affect like this.
Before posting to the halog, consider what might have caused the affect you are seeing. Small changes in the polarization like this are probably due to temperature, so look at the nose level, main flow, or beam current. Try to correlate what you're seeing with other things that are going on; avoid bothering the target on-call unless you are sure something is wrong.