The only answer is a poor connection. Period. Heat spreads from the poor connection. You may have screwed down the screw perfectly, but the connection below that may be poor, and with no insulation to melt, you won't know what is hot.
Get an infrared laser pistol shaped thermometer and point it around the connection, you will find the hot spot easily with one of those, and then know what you have to fix.
I bought one for only $30 on sale, and I use it to check my tires when running, my brakes and calipers, and all around my house to find where the cold comes in and the heat is hottest.
Mike
2012 Winnebago Impulse Silver 26QP
2005 16.6 Double Eagle
2018 Jeep Wrangler JK
previously Snowbird Campers,
Triple E Motorhome and Fifth Wheel