Swansea lost 1-0 at Cardiff City Stadium as Steven Caulker headed home the only goal against his former club.
At the full-time whistle the Swansea players went to go and applaud the travelling support, but, on his way to that end of the ground, Shelvey appears to make a gesture known as 'Swim away' towards the Cardiff fans.
The gesture is believed to reference an incident which took place in 1988 where Cardiff fans allegedly retreated into the sea after the two sets of supporters clashed.
There had been concerns over potential trouble betweens fans at Sunday's game, but South Wales Police tweeted on Sunday evening that no arrests had been made at the ground.
The tweet read: "No arrests at the Cardiff City Stadium today. Great to see both sets of fans being passionate & well-behaved".