After a few restarts, it cleared. Not sure why, but not seeing it anymore.

I too am getting this.
Not running out of memory:
[@ip-172-30-1-223 factorio]# cat /proc/meminfo
MemTotal: 1015472 kB
MemFree: 487068 kB
MemAvailable: 718780 kB
Buffers: 0 kB
Cached: 384428 kB
SwapCached: 0 kB
Active: 347136 kB

0.000 2016-04-09 23:42:25; Factorio 0.12.30 (Build 17998, linux64 ...