CFL bulbs flash slightly even when turned off
Any leakage current will cause CFLs to flash. I had to replace my porch light timer with a relay type because the sensor in my original one used a very slight amount of current to test if the bulbs were installed and working. And here's a similar problem I have been having, for which I have not yet found a suitable solution: I have some LED spotlights on a dimmer that ties in to a circuit with two other incandescent lamp system on dimmers.  Depending upon the setting of all three dimmers, the LED spots will flash. I think it is noisy contacts in the incandescent dimmers, and that small amount of pulsing is picked up by the LED circuit.  It is not annoying enough for me to delay any of my other projects to address it, as it only happens occasionally, and is mostly triggered by the chandelier setting.