If you've had him for a year and he ate perfectly the whole time, I wouldn't worry about it too much. Just keep a close eye on his weight and energy level. Snakes will sometimes do this for no apparent reason...when he's ready to eat, he will.
Chris
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0.2.0 Grey Rats-Lauren, Avril
1.2.0 Black Rats- Robert, Cady, Kylie
1.2.0 Albino FL Kings-Nick, Jessica, Ashley
1.1.0 Crimson Corns-Kane, Ruby
0.1.0 Het-Crimson Corns-Lola
0.1.0 White-Sided/Pos Het Albino Black Rat-Lita
1.0.0 Albino White-sided Black Rat-Rey
0.1.0 Fl King-Bonnie
1.0.0 Biak GTP-Brandon
1.0.0 Flame X Blood Bearded-Ruff
1.2.0 Ball Pythons-Donnie, Gretchen, Alexis
0.1.0 Red-tail Boa-Xena
0.0.1 Savannah Monitor-Izzy