Is this vase by Gunnar Nylund a factory second?  

Nylund vase
My understanding of Rorstrand factory seconds is that there will be a scratch through the Rorstrand or "R" hallmark or sometimes scratches in the foot of the pot.
I have a number of Rorstrand pieces and have never seen the x.

Rorstrand
With Royal Copenhagen, the x often meant "painted by". Could Rorstrand have done the same thing?

Could the X under the L be a...
Could the X under the L be a dare code? Again, with Royal Copenhagen marks under or above letters are used for dates.