It's a flood so far today, as carrier locked and unlocked Samsung phones in the US are receiving February patch one after another. In addition, the unlocked Galaxy S9 and S9+ receiving their first update after the Android 9.0 Pie OS upgrade.
This latest update for Galaxy S9 and S9+ brings February 2019 security patch that provides fixes to 12 Samsung Vulnerabilities and Exposures found in previous versions. Also, the update installs bug fixes and stability improvements to these devices.
The Galaxy S9 and S9+ are receiving this update with software version G960U1UES3CSAA and G965U1UES3CSAA respectively. If you want to check this update, please head into Setting > Software Update.
All of the carrier has already released Android Pie update for Galaxy S9 and S9+ but still the unlocked Galaxy Note9 hasn't received the update yet because Verizon is due to roll out the Android Pie for locked Galaxy Note 9, while all other carriers has already sent this update to the device.