that's common in most species,when you're talkng wild caught.....the babies often don't yet have a certain food item imprinted as their 'favorite'.....example-timbers grow to like chipmunks....edb's,strictly rabbits,etc...with the pygmies,the young are well known to actually prefer cold-blooded prey,like with many kingsnakes for example,or more similar to your situation,some of the smaller western rattler species...this 'imprinting' would obviously not apply to a captive bred specimen,if you're talking about adults;personally i view adult hots listed as captive bred with some suspicion-so many are actually wild caught...if they are truly captive,you have to ask,why are they being offered for sale anyway?