Sometimes too much adhesive is used when the safety seal is applied, causing the lid to adhere to the bottle. This can sometimes happen when too much heat is applied at the time the cap is applied. This was an isolated issue and adjustments have been made to resolve it.
In the meantime, to remove, carefully wrap a hot, wet paper towel around the lid for 5-10 minutes. The heat from the paper towel should loosen the adhesive and allow you to twist off the cap.