My question involves criminal law for the state of: CA

I received a DUI on 3/2009 and was put on the usual three year probation. I complete everything that the judge asked of me (fines, classes, etc). Just six months shy of the end of my probation, I was recently arrested for a misdemeanor vandalism. I hired a lawyer who was able to have the charges reduced down to PC 415(2) Disturbing The Peace. When I was arrested I was released on bail the next day. I was not told that I had been in violation of my DUI probation, not even when I went to see the judge, recently. I know that, technically, I am in violation. My lawyer said that there is a possibility that I may have to appear before a judge for a PVH. I guess my question is, is this for certain? Each arrest happened in a different city but in the same county. I don't understand why I wasn't told that I was going to have to penalized for my violation. Again, my lawyer says that there's a possibility that the City of Attorney of where I got the DUI will not want to do anything. How is this possible? I would think that it would be something automatic seeing how broke the probation.

I have no other arrestes or charges on my record. Is it possible to face jail time?