Hey John,
I've been told [?] that the clutch cables hardly ever go.
Keeping it simple, I'd review the adjustment procedure in the 101 projects, and note IF/when the problem re-occurs.
Happy path, nothing happens and your done
Otherwise, you're going down the path to "what-if" land.
One potential failure would be the fork that dis-engages the clutch plate is going, but I would hope that this was checked when the new clutch was put in, and can be ruled out.
Another potential failure would be something wrong with the pedal cluster and/or clutch pedal, but there is a 101 article for this as well.
Hope that this helps.