Hello,
If its the warning triangle with the circle round it, it could it be the traction control light which flickers when the car's traction control kicks in? It could loose traction as you go overthe speed hump (I would have thought that you would have to hit it quite hard/fast, which your not) I know from my works car you can get the this light to flicker quite easily, the power cuts, then kicks back in as the light flickers. Only an idea!!!!
Natty