Walnut Grip Numbers

[wisgro123]

I recently found a set of grips. The number 5 is stamped into the wood of the right grip. The left grip has a distinct capital A and what appears to be a worn upside down 5. Are these numbers significant of anything? I read in the FAQs and other publications that if grips are numbered it is usually with the last 2 digits of the pistol serial number.