Very strange/gross feedind story....
it happened to me on Friday. it was SO nasty, i had been chewing food when i walked over to Pandora's tank to see if she ate.. i wasnt really paying attention until i opened the lid and got a noseful of rat gut smell. i almost spit the food out that i had in my mouth and came SO CLOSE to throwing up.
its fine for the snake, dont worry. it happens all the time. maybe you thawed it too warm?? i know sometimes the rats/mice i have are squishier than others.
in any case, the snakes ok. im sure it didnt taste very well... ewwwwww