I think that the language in Act II.i foreshadows the future of Othello and Cassio's relationship. A gentleman says these words of Cassio:
And [Cassio] prays the Moor be safe; for they were parted
With foul and violent tempest.
Later, Cassio again refers to the great separation that the storm has caused for he and Othello:
The great contention of the sea and skies
Parted our fellowship—But, hark! a sail.
This great contention is indeed the storm, but the storm may be a symbol of that which separates Cassio and Desdemona. Cassio has indeed had feelings in the past for Desdemona, but he also has great regard for Othello. He would never make a move for her now that she belongs to Othello.
This scene demonstrates tension and themes of faithfulness and respect. Iago later in the scene demonstrates cunningness and is poising himself for great betrayal.