Two bubbles on my bubble coral have turned white ?

[Delphinus]

Possibly. If you move it, it might get cranky and close up for a bit.

It's been a while since I had a bubble coral, but, it seemed to me that they're fairly hardy. If there appears to be bleaching, I would actually move it away from the bright light and put it into something a little more subdued (under an overhang or something). Losing zoox. would be a little like washing off sunscreen ... suddenly you don't have the ability to deal with excess UV so you burn.

So ... if you're gonna move it, move it into some more subdued lighting (for now). Also, not too harsh on the current. Like most LPS I think they want a little flow, but a gentle flow.

I hope this helps. Good luck.