Just keep your eye on it. If/when it corrodes it's unlikely to stop the engine, corrosion is a gradual process, you will know "something isnt quite right" but it will be running, and will continue to run for that trip. Back in port you will have to appraise the situation and decide on repair/replace.
To reduce corrosion in my heat exchangers I fill them with a 50% antifreeze mixture every winter at layup, so far the results are encouraging. This should increase the life of the raw water bits.