Rabbit that looks and tastes like chicken?
It wouldn't be the first time that a high-end restaurant has passed off more expensive ingredients as cheaper ingredients, but it's pretty unlikely. What is the most probable reason is that you had farmed rabbit as opposed to wild rabbits, which have very different flavors and textures due to diet and lifestyle. 

Wild rabbits eat lots of grass and flowers which give their meat that gaminess, and they get lots of exercise running around so their texture is tougher and color darker. Farmed rabbits are given a mostly grain diet which is bland and makes the meat bland, and don't get much exercise so they are more tender.