If it's coming on at all, that's a good sign - at least means the bulb hasn't been pulled. That it's not coming on at other times based on what you've described is surprising to me.
Certainly sounds like something isn't right with your steering then. As previous posts have suggested, I'd be checking the boss and see if it is HICAS compatible. If you can't be bothered messing with all this - do as many others do and lock it.
For me, and many others, I'd rather my HICAS working - especially given having a HICAS lock-bar technically requires engineering to be legal. The HICAS system is fine on the street, and handy on the highway - it also helps keep the car straight in particular situations which can be counter-intuitive to how some people might expect. This can cause some unpredictable behavior in particular scenarios (on the track, drifting, etc), as the HICAS will essentially start 'fighting' with the driver about how to react.
Anyway, if you can't be bothered (many can't) - just lock it