We also just got back from the Eastern and no problems with sea lice, but we didn't go in the water at St. Maarten. At St. Thomas my DD(8) encountered a 1" jellyfish and had a small irritation on her arm. This was the day after our viewing on board of "Finding Nemo" so she called the jellyfish "Squishy" and said "Bad Squishy". The irritation lasted less than 24 hours.
Bruce