I would suspect that that particular miner is mining with v0.16.3.0 which has a higher BIP9 threshold. That particular node would continue signalling as if CSV/segwit is not yet enabled.
This is the version
v0.16.3.1-bb376f5
/Satoshi:0.16.3.1/
Those message appeared a few days ago
Edit: I reinstalled the client and the message is not there any more