Recent fuel injection service and...?

yes if the light flashed the car stored a code, take it to a real mechanic, not autozone, they are only gonna be able to read the code not diagnose this problem then they are going to delete the code making it difficult for the real mechanic to do his job, if the light starts flashing again stop driving the CEL light flashes for only one reason, a misfire severe enough to damage the catalytic converter, the fuel injection service did not make the problem worse but it did not address the cause of your problem (which is probably ignition related) and the defect is simply continuing to deteriorate