Tashigi

It's prob experienced here more, because you're using WASD and multiple keys more frequently and combining them. That can cause the driver to get out of whack. To add to the poster above, SS spam will fix that usually. You can also try pressing WASD in random directions while trying to control the camera with your mouse. The solution is to do counter the key input error, so the driver is forced to refresh.

It's not a game issue; more of a driver issue with some keyboards. It happens in almost every MMO I've played (GW2, AION, WOW, TERA, etc).