Question time for the product gurus! 
Does anyone have any sort of explanation for this? Photos taken with iPhone so they're not the best, but should get the point across:
The left bottle is about a year old (04/03/09 "born" date) and the right bottle I just received (03/17/10 "born" date). I took the picture after shaking both bottles vigorously for a few minutes. The old bottle is still about 1/2 full with product, and it has been stored in a cool, dry environment (basement). Is there any reason to not use the old bottle?
Couple more pictures:

Does anyone have any sort of explanation for this? Photos taken with iPhone so they're not the best, but should get the point across:

The left bottle is about a year old (04/03/09 "born" date) and the right bottle I just received (03/17/10 "born" date). I took the picture after shaking both bottles vigorously for a few minutes. The old bottle is still about 1/2 full with product, and it has been stored in a cool, dry environment (basement). Is there any reason to not use the old bottle?
Couple more pictures:

