What you are seeing is shedded suspended negative plate material lightly coated with antimony. Normal but it's like seeing an old man clutch his heart and then smiling "Oh good, it has passed".
Get your plans together. If you have tow service great. If you don't, muse how difficult or easy a no-start in some parking lot would be. This would be a perfect scenario for a (powerful for a diesel) emergency jump start battery. At least carry TWO GAUGE jumper cables if your vehicle is a diesel. Your vehicle is waiting for you to park in a remote parking lot at night in a rainstorm before the batteries go belly. Typewriter paper, thin starting battery plates just about show their ribs when brand new. A forced diet of plate shedding means the end is near.