Are you talking about SteadyShot, if so, I emailed Sony about this and below is their reply.
"I understand that you would like to know what the SteadyShot icon is indicating when it is flashing in P and A shooting modes.
The camera shake icon displays if camera shake is detected, insufficient light is available when preparing to take a picture, or when the shutter speed is set to use a 1/30th second or longer shutter speed. The icon will not flash when the shutter speed is set to 1/30 or faster in S (shutter priority) and M (manual mode).
Thank you for choosing Sony."