My guess is that the supply of dollars is lower. Businesses still need them to pay for goods and services with their primary trading partner. Rising gas prices in the US is causing less disposable income spending, and that effects the flow of US$ to the DR in two ways: 1) less travelers, and 2) fewer remittances from Dominicans in the US.
Supply and demand. Demand is stable (for now), but the supply of US$ is reduced.
There may be other factors involved, but the macro-level view comes down to that.
I got 34.35 @ Pichardo Cambio in Jarabacoa today.
BYW and FWIW: I totally discount the CB* manipulation conspiracy. Why? Because in a world where money changer work on razor-slim margins, there has been no black market developed for US$ or Euros. That is nearly always a symptom of money supply manipulation by a CB*.
*Disclaimer: the use of CB ^^^above^^^ is not a reference to ~moi~, although I wish I could.