I've had this a couple of times.
Not mains shock, but a lip tingle - being moist and crammed with receptor cells the lips are very sensitive to static and fairly low potentials.
These days a cause can be double-insulated gear 'floating' above ground, one cause can be both ends of a signal chain with a ground lift perhaps made worse by leakage across ans SMPSU.
Double insulated chargers can do this.
So perhaps start by checking the mic's ground is continuous with earth.