My vamo was just delivered today. I attached a vivi nova tank with 2.4 ohm coil head. The first time i checked, it read 3.7 ohms! I checked again & it said 3.1. Now its reading 2.6 every time, which is at least close to where it should be. Tried a 2.0 ohm carto, which the vamo reads at 2.2 ohms. Is this something i should be concerned about, or is it not a big deal?