There's a new firmware update available for Lumia 950 and 950 XL owners today. While it's a fairly minor update, it requires owners to use the Windows Device Recovery Tool (WDRT) to get it.
01078.00038.16082.360xx firmware release (March 2016) for Lumia 950/950 XL. Combines fixes included in 01078.00038.16025.390xx firmware and 10.0.10586.107 OS update to factory and repair channels (including Windows Device Recovery Tool). Not available via Over-The-Air (OTA).
As we can see, it focuses on fixes to the repair channels, so it doesn't look like it's anything that is going to improve day-to-day usage.
It's also not clear whether or not this firmware is available in all parts of the world or just select regions. Nevertheless, if you plug your device into a PC and run WDRT, you'll be able to see whether the new firmware is waiting for you.
This new firmware is also not on Microsoft's list of devices to receive firmware updates, so it's shrouded in mystery. We've reached out to Microsoft for comment.