did the krausen fall? If yes, rack away. I'm a fan of waiting for this to occur as opposed to counting bubbles over a minute but usually either is a signal to rack.
I just sometimes get an airlock burping at me every 30 seconds even though the krausen has fallen and when I hydro test it was done anyways. Suspect CO2 discharge from the trub (my opinion) as once its in the secondary it bubbles much less frequently.