Exactly right... The cruise lag is a common problem on the GL1800s, and is well understood by the Goldwing mechanics (and thus, easy to remedy). Since your bike is brand new (with warranty), you should be able to have the cable adjusted for no cost to eliminate the deceleration after setting it. I had a 2003 GL1800 with this problem, and I paid the Honda Tech to fix the problem...
Congrats on the new F6B! Rick