Originally Posted by bikinpolitico

When you change the flat, are you running your hand along the inside of the tire to ensure what caused the flat is no longer there? That may have been the problem. Also, check you rim tape. If it's one of the rubber band or plastic kinds, replace with cloth rim tape. Non-cloth ones are often the culprits with frequent flats.

I think you where right to replace. Once a tire gets a largish whole like that, I always replace.