me too, but I think it comes from letting off the gas and you get a little bit of spitup like when you burp, if you don't do as much of the goosy lucy it should be less.
same sled, same thing. It is normal as far as I know. I have owned other sleds that do the same thing. As long as you don't have a swimming pool in the box and the sled is running fine, I wouldn't worry