Take it from somebody who lived in Central Florida, saw hundreds of rocket/missle launches at all hours of night and day, under all sorts of lighting conditions, over 50 years - that is exactly what a rocket/missle launch looks like. I'd be more inclined to believe it was swamp gas or a weather balloon, than believe it was an airplane.
My bet is that it was a Trident SLBM launched from an USN Ohio Class sub. The time and location were chosen to send a message to those who might think that the USA is becoming soft and weak, that we are not.
"The USA is still top dog with big teeth. You want some of this?"