Possibly similar to Should a smart switch (that requires a neutral wire) cause my non-contact voltage tester to beep? but slightly different symptoms, and only on one switch.
After installing Leviton D26HD smart dimmer switches, running an NCVT-2P voltage detector pen around the front outside of the switch where the switch meets the face plate, it detects something on both sides half way up. But not on the top and bottom. And it doesn't detect anything on the other dimmer switch in the other room.
If I pull the switch out, the voltage detector beeps near the line and the neutral parts of the switch's sides (it has built-in wires, not terminals), but not near the load or ground.
Suggestions? Do I need an electrician to check?