Copper piping that carries water, in a space that can go below freezing, is a bad situation just looking to get worse. Worse being the water eventually freezes and splits the pipe leading to a leak and ceiling damage.
If there are no viable other ways of running this line (in a heated space) to a drain I would suggest having the entire exposed line run in vinyl tubing or PEX tubing.
The other thing is a maintenance issue. If it took 12 years for this to happen I would strongly suggest you look at the end of the line where the water discharges. It's possible that bugs, bees or something else has plugged up the end of it. Small diameter piping/tubing that has a drop to it will auto-siphon once the condensate pump shuts down usually clearing any standing water out of the section of it that is in the attic. I'm suspecting something (the end being severely restricted) has stopped this process from happening. The other thing that can cause water to stand in the pipe would be a large build up of "crud" in the sump of the pump. Again a maintenance issue.
If you find bug or bees in the end of the pipe outside a simple paper clip slid into the end will most times make them loose interest.