What are the implications of an encrypted private key being released?
Since the encrypted key file is (potentially) leaked, and adversary is able to run an offline dictionary attack against your key. So you have to answer the question: Is the strength of the password used to encrypt the key, weaker than the strength of the key itself?

So what you should do, is calculate the strength (entropy) of your password (KeePass can do this, for instance) and compare it to current strength estimations for the itself (RSA 2048 has 112 bits, for example). If the password's result is weaker then the key, you should drop it and revoke the certificate.