I'm not sure exactly what happened with OP's flight, but this has been a wacky weather week in Japan. Most of the country outside Tokyo got racked with historic snow early in the week -- CTS shut down completely on the 11th and a bunch of people got stranded. That probably messed up JAL's operations especially for domestic A350s, many of which are deployed to CTS.

Tangentially related: on Thursday, Tokyo was hit with gale-force winds so bad that trains were being forced to slow down. I was riding the Keihin-Tohoku toward Kawasaki and saw a LH 748 taking off from HND, and it appeared to be hovering in the air...