I drink aloe vera juice all the time. Was the date on the bottle expired?
It doesn't sound spoiled to me... it sounds like part of the aloe didn't get mixed up into the juice.
I grow it and some times use it fresh. When I use it that way, I have to cut the outer leaf away, and the inside is has a pulp-like substance that sounds like what you saw. It doesn't come out in the form of juice, although it is juice-like.
If it didn't taste bad or smell bad or make you sick I'm sure it was ok. I've never had it go bad on me - I think it stays good for quite a while.