you are meant to give your hamster some salad, not loads, and not all at once, but a bit is good for it.
i've had 3 hamsters up to now. the first one died of wet tail, and we'd had him for 2 years. he somehow managed to damage his foot and started trying to chew it off just before he died.. it was uh.. not nice, but there was nothing we could do.
the second one also died of wet tail at a year and a half, and the last hamster i had bite of my dads finger and died after 3 weeks.. we think because my dad has to take quite a few tablets for his ME, it didn't agree with the hamster.
i'm sure your hamster just died of natural causes. they don't live much over 2 years anyway, and i'm sure it would have had enough food stored to be able to survive.
on the same subject; my neighbour went away for 2 weeks and left his parrot in the charge of his son.. he came back and the parrot was dead because he didn't feed him at all. at least it wasn't a £500 parrot!