It does say that if that error code occurs, the gas valve is "mechanically" stuck open. Since they replaced the gas valve, checking connections would be good as suggested.
It could also be a mainboard issue.
There looks to be a manual shutoff valve on the gas valve. If you can get to it, might be worth shutting the gas off when this happens to see if the error clears. If it doesn't, then it could be a false error and a mainboard issue.
If the error does clear when you shut off the gas valve, then you know the gas valve is staying open when it shouldn't. That could mean you got another bad valve or the mainboard isn't calling for it to close when it should.