High risk pregnancy last time due to abruption. Am I at risk again?

Yes. Placental abruption is poorly understood and unpredictable. The risk of recurrence has been reported to be 5-15%, compared to a baseline incidence of 0.4-1.3% in the general population. After two consecutive abruptions, the risk of a third rises to 20 to 25%. When the abruption is severe enough to kill the fetus, there is 7% recurrence risk with the same complication. Aspirin could help prevent it.
Possibly. Abruption can be caused by numerous reasons. The most likely is unknown. Some of the others include abdominal trauma, uterine anomiolies, elevated blood pressures. Ask your OB they could give you a better reccurrence risk after getting a indepth history of your prior pregnancy with the abruption.