If you don't have a promise in a handbook or document from your employer as to PTO rights, then this PTO benefit can be applied as the employer desires. Look to see if you have any promises made on that. There does need to be consistency. It would raise questions if it was not applied to everyone in the same manner. Sucha benefit is not normally a vested benefit and can be changed by the employer.
More facts need to be known so do not rely on comments here until consuting with an attorney that practices regularly in this area of law.