I don't have H-croc but like ombre lizard (which I have) there will be a slight natural 'yellowing' over time. It's a process of oxidation. You wouldn't notice it by itself, but when you put it next to a new bag you would. Whites in general do this, which is why traditionally leather shoes and bags were made in ivory in the first place and not white.
There are people who would (and have) sold their entire H collections for one H-croc bag and for others, the ultimate crowing glory in a vast array. IMO, if you're not obsessed with Himalayan croc, it's not the choice for you.
There is a darker type of H-croc if your SA can find you one.