I have a unlocked phone direct from Samsung and received this update two days ago. Im with Vodaphone PAYG now.
Same as here Sim-Free from Vodafone Ireland and have had two updates this week, the Security update for MArch was a few days ago now.
They pulled the update for a bug fix then re submitted it, you may have received both. Looks like vodaphone are first to the show then this time. Although thought it didnt matter when sim free