Metro had more to apologize for on Thursday evening.
A power outage temporarily shut down its radio communications, causing delays late Thursday on Red, Orange and Blue lines.
Trains were stopped for about 15 minutes just before midnight -- but because trains were already single tracking at the time, riders saw major delays.
Some riders tweeted they were sitting in train cars for as long as an hour.
Metro said it was investigating the cause of the power outage, which affected computer systems, radio consoles at bus and rail control centers, and the its website.
In a release Friday morning, the agency wrote: "Metro apologizes for the inconvenience experienced by customers during this time."
On Thursday morning, Metro riders on the Red line experienced significant delays when a rail cracked near the Van Ness station.