Quoting from one of my other replies here:
Still, this is absolutely not the ideal situation in terms of the utility of SBD as a stable value token (and indeed it appears to have demonstrated more temporary upward price instability than other pegged tokens). I don't think anyone would disagree there.
As noted by @timcliff in the post, perhaps other changes can be made in the future to reduce the upward spikes. Even without changes I do think it is possible (though hardly certain) that the price may become more stable over time as the system matures.