I've been using boge cartomizers in my tank for a while and they have been working well for me, but recently I've noticed the longer I use the carto the ohms are lowering (using on a provari so can check the ohms). Is this something that happens naturally that I have not noticed before? The carto that I am using today started at 2.2 ohms and now it reads 1.6 ohms. Is it because the carto is getting "gunked" with my 50/50 PG/VG eliquid?