I'm sort of guessing, OP may have had weird contamination in his Dektol. Either that or he developed an Xray generating organ on his body and fogging the paper himself.
Cool, I should go to "ripley believe it or not" TV show. With the money I make I will be able to afford a proper safelight and fresh Dektol.
Yes, that light had been working just fine until that day. I am guessing something happened in the filaments inside that are glowing past the red coating. Maybe I dont know what I am saying.