Mistakes happen, you just hope it doesn’t matter:

A staggeringly basic blunder is delaying the grand opening of the MTA’s first new subway station in 20 years, the Daily News has learned.

The platform at the $530 million South Ferry station is a wee bit too far from the train tracks, officials confirmed Tuesday.

Recent inspections found gaps between the platform and No. 1 train cars up to 1 inch wider than federal rules allow, the Metropolitan Transportation Authority confirmed.

Riders will have to wait another three to four weeks before they can use the station while workers make some $200,000 in fixes, the MTA said yesterday.

Location Scout: South Ferry Station.