Many years ago the US Army refrained from staining the backs of leather goods for that reason too. I don't stain any of the inside of my gear that I make, unless the customer insists on it, for that reason also!
The reasons are numerous and some have been mentioned here in part. A lot depends on the type of leather used and the dye used and how you sealed the leather after. Undyed or natural oiled leathers usually don't present that problem either. Some dyes have a tendency to bleed for a long time after being finished, regardless of what you do to correct it. Sometimes a cleaner and application of Sheen will take care of the bleeding.