Hi -- I wouldn't be worried by that it's not as if you have deceived them by trying to get a lower premium.
The registered address on V5C is more crucial for the Police or other agencies to send speeding tickets or contact you, ie when your road tax is due to expire, it does not affect the risks of where the car is kept for insurance reasons. The same would have applied had you forgot to amend the address on your driving licence, you would still hold a licence therefore it would not affect insurance.