I am a new salaried employee and not quite sure if my employer is allowed to do this.

Recently my company had a shut down for the holidays. All hourly employees were told they would need to take a vacation day or personal/sick day in order to be paid for the days not covered by holiday pay. Understood, but they then required me to do the same. Since I am salaried I do not have personal/sick days so they required me to burn a vacation day in order to be paid for the day not covered by holiday pay. Do you know if they are allowed to do this? My understanding is that I am salaried exempt and receive the same amount of pay during any month no matter how long or short. Why would the company shutting down for a holiday break impact my pay?