You just need to drive it for a few weeks, maybe less.
There is a code in the computer on all OBD II cars known a P1000. It means that the monitors have not run. Some of the tests that the OBD II system has do not run all the time. They run intermitantly and in order. When one is completed, another one can start, but only when certain conditions have been met, such as driven for so many minutes then brought to an idle. Depending on you driving habits and needs it can take a long time for all of the monitors to run.
The P1000 will set if the battery has been disconnected or if the codes were read and the light reset.
I'm surprised that the smog shop did not explain it to you better. Around here, many don't charge for the test if P1000 is present, they just tell the customer to drive some more then come back to be tested.