Tracked Builder sometimes sounds like a wheeled bot

[Cheker32]

The tracked builder sounds like a wheeled bot when it starts moving if you don't have it selected and when you switch to it while pressing any direction key.

Procedures to replicate
1:
-execute code on the tracked builder to have it move (wait and move will do);
-switch to something else nearby before it starts moving;
-once the builder starts moving, it will sound wheeled.

2:
-select anything other than the tracked builder;
-press and hold any direction key;
-while still holding the key, switch to the tracked builder;
-the builder starts moving, sounding wheeled.