ich - blue tang?

[btymens]

Saturday my blue tang was fine, this morning when i went to feed him, his was covered in white spots which i looked into and it looks like ich. However in a span of 2 hours, most of the white spots have disappeared. So my question is to those of you who have dealt with this, is this ich or stress releated. I am a "newbie", I've had my tank for about 1 year now, so some sound advice would be nice
thanks