It looks like one of two things to me...
Either you accidentally splashed some water on the paper after it had been coated and dried (before or after exposure) or the negative had some water droplets on the emulsion side.
If the negative had water on it, or if the paper were wet when you assembled the sandwich, it would have stuck to the print a little, so you would probably have been aware of the problem, and that sinking feeling in the pit of your stomach is the realization that you just ruined a negative.
If you splashed water on the paper before, you probably would have noticed the spots in the coating if you were paying attention.They are pretty obvious as areas of lighter coloration.
My guess is before you placed the print in the developer, you accidentally splashed the surface with water. The water starts to clear the print without development (other than the printing out). Even a fewe seconds of water will ruin the print, so getting a splash on it while placing in the tray to develop could do it.