possibility 1. he had been fed already. try again next week.
possibility 2. he is going intshed. try again next week if no change.
possibility 3. the guy that you bought him off of did some crazy stuff (dancing rodent, fed in the dark, played the banjo, etc) with the mouse while feeding the jcp. email the guy and find out.
possibility 4. the guy you bought him from straight-up lied to you because the snake was a problem feeder and he didnt want to have to deal with it so he dumped his problems in your lap. it happens.

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0.0.1 Colombian Redtail Boa
1.1.1 Sumatran Blood Pythons
1.0 Black Blood Python
1.0 Dumeril's Boa
0.1 Coastal Carpet Python
0.1 Jungle Carpet Python