This doesn't, I think, mean much of anything, but I hadn't seen it before. One of my variegated Agave americanas grew a couple leaves that got fused together halfway down.
The new leaves on the Big Damn Screw Pine occasionally fail to separate from the leaves that precede or follow them, I think because the midrib spines get caught on the other leaves. If it were growing outdoors, where the wind and rain would move the plant around as it grew, this wouldn't be a problem, but indoors I occasionally have to unstick them from one another. So, I thought maybe the Agave situation was something like that, and tried to pull the leaves apart.
But I shouldn't have. Oh, well. The plant hasn't rotted or turned yellow or started to glow or anything, so it appears that I didn't actually hurt it.