Did Dobby apparate?

[nera at rconnect.com]

No: HPFGUIDX 18083

In CS, The Rogue Bludger:

    "'Dobby must go!' breathed the elf, terrified. There was a
loud crack, and Harry's fist was suddenly clenched on thin air. He
slumped back into bed, his eyes on the dark doorway to the hospital
wing as the footsteps drew nearer."

Did Dobby apparate.... within the boundaries of Hogwarts, since they 
were in the infirmary? tsk tsk tsk ... I thought nobody could do that.

Doreen