The situation is perfectly fine, and indeed there is no need for you to export the private key and re-import it.
You always have the private key of change addresses, and you can spend your bitcoin (no matter it is your normal receiving addresses or change addresses) anytime.
https://en.bitcoin.it/wiki/ChangeThe wallet file contains the private keys for change addresses, and they can receive and send coins normally. However, the GUI in the default client does not display them in the address book.