Generally, the flashing O/D light means that the ECM has detected a failure with something in the tranny. Most often, this is a sensor, but can be something mechanical or hydraulic. It's really hard to pin down.
What I would do, is continue driving the car and see if it (flashing O/D light) happens again. If it does, take it to a tranny shop or a shop that you know of that can hook a OBD-II scanner to your car and "read the data stream while driving it". This is the only way to find out what the flashing light actually means.
The jerkiness that you noticed is normal, after a flashing overdrive light, because the ECM goes into "Limp Mode" (aka Fail Safe). This limp mode program, in the ECM causes the tranny to run the line pressure a lot higher than normal. This higher line pressure is what causes the jerking. But it's actually not jerking, just engaging the clutch packs alot firmer than normal.
Best of luck!