Why did the resistance go up on my inductor?
Eddy currents circulating inside the core produce resistive losses but only circulate when there is AC to induce current flow in the core.
(The difference being energy consumed due to reactance is recovered some time in the future when the energy is released back into the circuit by the inductance/capacitance whereas energy consumed by resistances not recovered. The meter detects this difference when instantaneous readings are averaged out and examines how much power consumption was cancelled out over time and how much was not versus the total amount of power flowing.