Ashful - Nice catch! Thank you. Thought I knew what I was doing, but I didn't. Back in the day, it seemed that mfg's spec manuals specified some lubricant before torquing. Then they listed the torque values for each fastener. I just extended that to spark plugs.
I just checked and found information from NGK where they specifically state NOT to use any sort of anti-seize before torquing a spark plug. They warn that doing so may result in over-tightening and damage to the plug and/or cylinder head! They also said that all NGK plugs are treated with corrosion resistant plating, so
do not require any corrosion protection.
I've been using anti-seize on spark plugs for probably 40 years and have not had a problem, but I'll never use it again. I always torque to the low value in the range and perhaps that's what's been saving me. There's just something about a steel thread spark plug screwing into an aluminum head that has always made me cautious.