It reminds me of Hamlet's last words in the Folio edition:

    O I dye Horatio:
    The potent poyson quite ore-crowes my spirit,
    I cannot liue to heare the Newes from England,
    But I do prophesie th'election lights
    On Fortinbras, he ha's my dying voyce,
    So tell him with the occurrents more and lesse,
    Which haue solicited. The rest is silence. O, o, o, o.

It has been suggested that the final four "O"s were inserted as a Christian reference to the pure joy expressed upon the revelation of death. One hopes this is what Steve experienced.