I measured three inductors from 20hz to 100Khz, and compare the values in free air and resting against a double sided printed circuit board. Note that the inductance drops quite fast starting at about 1 KHz for all three. Also note that all three start to decline even in free air after 10Khz, this due to proximity effect current redistribution, the current it attempting to travel along the least reactive path, which is one of lower inductance. The wires limit the amount of actual inductive drop that can occur due to proximity.