Last night I made a dual coil SS316L build and I have experienced exactly the same behaviour. The cold ohms were reading somewhere in the mid 0.175 area when initially built. After a tank or so the cold ohms had dropped down yo 0.165. By this morning when I did a cold read they had dropped down to 0.160 ohms.
So I have now seen this with mesh and Twisted Clapton (3-28/38) coils.
As I have said before, now that I have sorted the cold ohm, it's working just fine in TC. Just took a while to settle in.
Out of curiosity, how long do you leave the atty before measuring the cold ohms?
I give it at least 15 mins. It's that bit that I find annoying tbh.