[mrlmd1]

Probably the leak was known by the previous owner and never disclosed to you, and that may be the reason he decided to sell it, rather than repair it because of the expense. You should confront him with that, or if you got it from a dealer, confront them. That is fraud, misrepresenting the condition of what you purchased, but you probably bought it "as is". Doubtful you caused the problem pulling a piece of gasket out, probably due to loose bolts. Just keep an eye on your oil level and the size of the leak over time.