I love it when that happens to me :)
(Currently fighting off the three-years-overdue third book in a trilogy because I can't write it until I finish the next four books I've got under contract ...)
I've been following your adventures with the new trilogy -- and the various attack novels -- with much amusement and sympathy!
Brains are funny.
Mine is handing me images and ideas from the sequel to this yet-unsold novel.
Everyone loves the premise and snippets you've posted for the yet-unsold novel, so I think you're fine!
But like you, I need to finish the first book before I even think about writing future scenes. :)