Brain fart

Today I went and picked up my tent trailer at the shop. They replaced a electrical element in my fridge. I thought I checked all my pre tow duties. Obviously I halfa**ed one. I get 1/2 mile down the road and I heard a funny sound from the trailer. I looked back and saw the front of my trailer going up and down. I knew right away the trailer was not fully attached to the ball. I tried to coast the truck until I could get it to stop without touching the brake but I was to close to a red light. At that point the trailer came all the way off the ball and the chains was the only thing keeping it from dragging or hitting my truck. I realized at that point that when I lowered the trailer and moved the truck slightly to seat the trailer on the ball that it had not seated all the way. This time I made sure that the trailer was firmly attached to the ball. You would think after many years of towing utility, tent, and travel trailers you would not make such a bone headed mistake. Well live and learn. No harm no foul.