When did you last earn any new points?
Frontier announced that Beginning March 7, 2015 points would expire six months after the last points earned.
A date of 11/16/2015 implies the last points were earned on 5/16/2015, after the change in the program.
A date of 4/1/16 means the last points were earned on 10/1/15 again after the change in the program,
Likely these points pre-date the change in the program and the date was never updated in their computers.
Previously points expired after 18 months. 4/1/16 would mean the points were earned 10/1/2014. However when Frontier announced the change in the program they also said:
if you don't acquire new miles by September 7, 2015, the miles you've accrued through March 6, 2015 will expire on September 7, 2015 and won't be available for use.