They updated the FAQ to say:

As the world’s largest confectionery company, Cadbury Schweppes is committed to developing great-tasting products that consumers love. Since people’s preferences vary from market to market, so do our products. This is reflected in the broad variety of sizes and flavors of products that we offer our consumers worldwide.

If you’re eating a Cadbury Crème Egg in the UK or Canada - nothing has changed, they’re the same size as ever. However, in the United States, our business partner, Hershey, elected to reduce the size of the crème egg.

Cadbury Eggs remain a consumer favorite and continue to be an excellent value. We apologize for any confusion or misleading information.