Yep, most likely.
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Oh, you knew I couldn't leave it at that!
The grease should be fine unless it has been exposed to water, in which case partial re-saponification of the soapy incredients can occur, despite the waterproof claim. Yes, Phil grease is essentially waterproof, but can still separate with prolonged water exposure. The clue this has happened is it turns a minty green closer to the color of the tube than the grease. Don't use it in this case.
Heat in storage is a factor as well, and can cause some separation into oils and solids if extreme or long-lasting. I had a tube separate when stored on a windowsill one summer when we had several days with ambient temps of 38°C or more. It was probably much warmer on the windowsill. Despite kneading the tube, I couldn't mix it back to original form; it remained like mayonnaise that has been through a freeze in the garage larder. Don't use it in this case.
If the cap has been left off, the more volatile ingredients may cause a thickening of what's left. If it feels gritty when rubbed between thumb and forefinger, don't use it.
If the tube's contents are still cohesive and it has the usual "Phil smell" (one of the best-smelling greases ever produced, as Andre will readily attest), you should be fine and can use it without worry.
Best,
Dan. (...who shares a last name but no other connection with the company except as a satisfied customer)
