Yes, that's most likely where it's coming from. That's relatively normal, I guess... meaning, I've seen it happen on a lot of guys' bikes. You may be running rich if you're getting a lot of that, atleast consider getting some new jets.
But you can either try adjusting that rubber boot, it may be on backwards... on mine, the inside of the rubber thing has a lip that rests up against the end of the exhaust pipe. If you take it apart, you'll see what I'm saying. Or you can put zip-ties on both sides of it, and it shouldn't leak anymore.