I get this question frequently so I will post the question and then answer myself:
"I made a mistake and did not notice that the LT3080 datasheet says for the DD PACKAGE that "EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB". I made my pcbs with the exposed pad soldered to GROUND instead of OUT but the circuit still works - Do I need to fix the pcb?" I show the LT3080 datasheet Pin Configuration for the DD PACKAGE in the image below:
...just remove one tag.
[edited by: ARad at 5:07 PM (GMT 0) on 10 Dec 2019]