steering problem
 

so along with my local hobby shop, I built a new racing 1/8 scale nitro buggy and am fairly new to the rc world. I notice that any bump to my front tires throws the steering off alignment (so its moving the servo horn?). In order to correct it I just move the wheels back to straight and everything is great. But if Im going to race I cant have that happening...Does anyone know whats going on?...