No you are not a bad parent at all. I believe it is right to correct them, incorrect pronunciation of words will only make it difficult for them when they have to spell words. So by correcting them, you actually make life easier for when they have to spell. Not saying that it is not cute when they say things in their own ways. I very casually correct my child by just repeating the word in the correct way, no stress or pressure on them, and if they say it wrong again, I do the same.