My guess would be old. When I bought my tub it was entirely moist and tacky.
My tub is almost 2 years old now, the plastic tub a bit deformed from me kicking it to try to pop the top off in winter, so it doesn't have the most air-tight seal any more. While the old bits along the upper inside edges are a bit firmer and dryer feeling, its all still very pliable and useable after all this time... nothing is crusty.
Ask yourself: "Can I do anything about this?"
If you can, do it. If you can't... then you can't and leave it at that. Worrying achieves nothing but stress.
Mine dried out a little bit at the top once I opened it and then got some of it on the edges so I couldn't really screw it on tight anymore. The rest underneath that layer stayed very moist, and even the drier parts were still mostly pliable and usable, and it worked just fine as far as removing soreness in my mare's feet.
You might have to warm up the container and mix the ingredients with a large spatula or wooden spoon. The liquid separates and falls to the bottom of the container and the packing "floats" to the top. Hot tap water should be enough heat to soften it to mixing consistency.