On the 10th anniversary of the 9/11 attacks, American fighter jets and FBI command centers once again went on alert when crews of two separate planes of different airlines reported suspicious activities of passengers.

Two fighter planes were scrambled to escort an American Airlines plane from Los Angeles to New York after the pilot called with suspicions over some passengers' frequent trips to the restroom.

The precaution turned out to be unnecessary as federal air marshals aboard Flight 34 from Los Angeles to JFK were able to resolve the situation when the passengers complied with their instructions, ABCnews quoted police officials as saying.

Two Israelis and a Russian man were questioned at New York's John F. Kennedy Airport and then released.

One more pair of fighters had to hit the skies around the same time when the North American Aerospace Defense Command received a second call from a Frontier Airline flight from Denver to Detroit. The crew noticed two people spending a suspicious amount of time in a bathroom.

Instead, the suspicious behavior was two people making out in the bathroom mid-flight, law enforcement sources told ABC News. Three people were taken into custody for questioning, Frontier Airlines said in a statement, but no arrests have been made in that case either.

Due to the anniversary of Sept. 11, all precautions were taken, and any slight inconsistency was taken seriously. The public would rather us err on the side of caution than not, FBI Detroit spokeswoman Sandra Berchtold said.