Would changing your own oil a few times void the warranty on a certified used Toyota?

[schurrejason]

Have a 2005 Corolla. Started making some weird knocking noises on the way home. Local shop said the engine was going. I called Toyota, and they said it had a powertrain warranty on it still so I had it towed to Toyota. They said that if they need maintenance records, and if anything looks out of place, it might not be covered. I don't have records of changing it myself, which was like 2-3 times. Will this void my warranty? I sure hope not!