Almost certainly a longevity record, as least in terms of what's been formally documented. Salmon et al. (1997, link to paper here: http://www.sierraherps.com/bibliography) report several snakes that are around 20 yrs of age. Your animal at minimum is 29 yrs (28 in captivity 1 yr in wild), but likely 30 yrs old. PM sent.

Cheers,

BH
SierraHerps.com