This slide show to a military briefing on Odyssey Dawn says 12 American Navy ships are supporing the operation. Nine ships are shown on a slide, indicating that the three American submarines (2 SSNs and the SSGN (converted Ohio class boomer) U.S.S Florida) are also in theater.
But given that Florida was most needed in the first day volley of cruise missiles, I'd bet that the submarine has mostly depleted her stocks. It would make sense to fire off Florida's missiles to preserve the smaller magazines of the other ships and subs for the long haul of smaller scale strikes while Florida goes off to reload and redeploy for other missions to keep other potential foes off balance.
But then again, we wouldn't want to highlight where the sub is. I imagine Florida could be quite a distance away sailing off to reload, and technically still be claimed as an asset for the war.