I guess it's the thought that it's possible that's causing me to worry. I try to rationalize it by saying a few things:
1) Water (or liquid) has to go WAYY up your nose, and I don't believe it did for me because it didn't burn like it normally would.
2) Probably hundreds or thousands of people use neti pots everyday with regular tap water and they don't get it.
3) Hundreds or thousands of people go swimming everyday and get water up their nose and don't get it.
4) My ice was from filtered water out of the fridge which is known to kill cysts.
...Still freaking out. I'm afraid I'll freak out for the next week.