Margaret is correct, pH goes up in high SCC milk. Also usually has higher conductivity.
Is this very fresh? Meaning not stored for long? How old, hoe stored before make?
Milk has natural enzymes that facilitate protein and fat breakdown. When that sits around without pasteurization, it will start acting on the proteins. It's actually good for the first 12-16 hrs after milking because it should give you a higher yield due to higher casein hydration. However, after that, proteases that break down protein go too far, and do the job that lactic acid would do naturally from bacteria. And so you get this pre-broken down type casein that is prone to degradation and will stretch readily. Usually, higher protease is present in extended lactation milks. With your longer lactations, it's really hard to say without tests if that's true. There's almost no published research on extended lactation.
Might be the season, or feed, or hormones, or bad meter reading that's affecting pH.