it will also depend on what you use to check the pressure, and what temp the bike is, if its been ridden that day or not,
the shocks only carry a very small amount of air, the guage you use will take a bit of air each time so if you check it alot it will drop down.
i have had the HD pump on bikes for the whole day and the pressure increased 2 psi. as the day warmed up.
if you check it hot VS cold the pressure will be different.
if you check it before and after riding the pressure will be different when the shocks heat up.
you have to use a no loss fitting on the pump so it wont let any air out when you disconnect it.
i would say they arent really leaking its just variation in measuring from heat and the small amount of air each time you check it.