I can look at it and tell it is a repot. Does not mean it is a bad tube. Many tubes are potted by third parties. When we say repot it is generally meant as a rebuilt tube. In some cases it is a completely new tube potted by someone other than L3 or ITT. In any case the module is always good and what they are replacing is the elastomer potting compound and the power supply (tube electronics).
No way to tell whether the tube has new or used components inside after they pot it. If it works well I would not worry about it.