I ate expired piece of white chocolate? i noticed after eating it that it expired 2 months ago should i worry?

No: Chocolate doesn't expire like chocolate milk expires. If the "use by" date was 2 months ago, it should still be fine to eat. Other factors to consider include how the chocolate (or other food item) was stored, if it has been opened already, whether it is a solid, a semi-solid, a liquid, etc... For example, a chocolate bar stored in the glove box of a hot car for 2 summers could taste rather nasty.