I think its normal to ask that. Not only Nepali, anyone when they meet people from their countries at different land can ask such question. Even foreigners who come to visit Nepal ask each other how long they been in the country.

@user01 is perfect example of one of those types to stay away from. Kura k ho bujhna chaina paccha bolyo "Nepali ppl yesto usto". Kun ppl chai 100(saye) goon le varipurna huncha huh??