No there is nothing wrong in buying a "made in china" laptop of dell or any other company such as hp, acer, asus etc. The companies are setting their factories in China because of the low expense to operate one from there (low tax, utility bills etc)
As for your other query, yes it is normal for your laptop to show 316 days of warranty listed on dell's website and not 365. reason for that being is because the laptop you bought spent considerable amount of time on galaxy's shelf. however, you are eligible to claim warranty for a period of 365 days from the date you purchased it, but for that to take place you will need to keep the invoice handy as warranty will be claimed based on that. But if for some reason you are not content with the above explanation and want to see a full 365 days of warranty listed on dell's website you will need to contact galaxy and mention the issue to them and in return they will either get the date right by contacting dell or provide you with a relatively new laptop which has close to 365 days of warranty, the latter is however pretty unlikely to happen.
p.s. I bought a Hp DV6 from Bahrain and upon checking the warranty on hp's website, it was close to 340 days instead of the usual 365 days. But since I was aware of the whole process a laptop has to go through, the whole issue was of no major concern to me at the time therefore I lived with it happily.