Flight to sun from main planet requires more time compared with flight same distance from main planet in opposite direction. It is hardcoded effect of game engine per se - Torus flight velocity actually is not fixed 32 * maxSpeed ratio. Torus flight velocity increases with distance from nearest celestial bodies.
If you have Navigation MFD you can see acceleration/deceleration affecting ETE (Estimated Time En-Route) value.
NPC ships never uses Torus drive so you'll always taking mass-locks from forward direction. In any case Torus will engage after contact leaving scan radius and it is a matter of few seconds to build enough distance for "clear" Warp velocity. So I think it is no reason for additional direction check.
Never observe this phenomenon. Hope you'll investigate reason of this problem.I also observe a strange phenomenon during torus mode where sometimes ships behind me will appear to fly rapidly forward in the direction I am traveling, and disappear into the far distance ahead.
Thank you for feedback!