Yes, she probably did. So did mine. What your grandmother did is called the "inversion method" of canning and it was commonly used by home canners up until about the 1950s. The inversion method often creates a false or incomplete seal that can allow contaminants to enter the jar. The boiling water or pressure canning methods create a complete seal that better protects the food from contamination and ourselves from botulism. When we know better, we do better.