People have been buying UAE Dirhams like crazy. Deposits are being converted from rials and dollars into dirhams. The dollar is being dumped.
The UAE's central bank governor has gone on the record their intention to consider a revaluation of their currency, preferably in a joint move with the other GCC states, but that they will act on their own if the other states don't come into an agreement with them. [link]
Oman's silence on the issue is hitting a nerve with people and they are reflecting it by shifting their deposits into dirhams. This is a clear signal that the lack of transparency is leading to a loss of trust. They're afraid of losing out if our neighbors revalue their currencies and we get left out with a lower valued currency leaving us with a rial that buys us less of everything. Additionally, should the UAE revalue and Oman doesn't, there's an arbitrage opportunity. Even if Oman follows up with a revaluation of its own, the shift to dirhams is still a hedge because at least they (the UAE) are telling us that it might be coming while we (Oman) are totally silent about it.
Earlier this year: Currency revaluation talks