Hoping all is okay- Spark Plug Installation Question

Well I just replaced my spark plugs with the NGK plugs from Beemerboneyard and since they were not the Bosch plugs, I coated them with anti-seize. I failed to read in the manual until after I had already done the wrenching down . . . but I torqued them to the full 20 NM. The book indicates to reduce torque value by half ( ie 10 NM) when using a lubricant on threads.

Do you believe I now have a problem with the threads? How can I tell if I did any damage? I have since loosened the plugs and installed them at the half value indicated.

Also, should I buy new plugs due to the plug gasket having been compressed too much?

James