Well, it flickers on and off till the engine is up to temperature...... Oil is not that old.I wouldn't really worry about it yet, as long as the light is not on when the engine is running. It might mean your oil is getting a bit old or your oil pump might be starting to go out, but again, as long as the light isn't on while the engine is running I wouldn't be worried.
Then I would be worried. Keep in mind you said in the original post it flickered only when starting.Well, it flickers on and off till the engine is up to temperature...... Oil is not that old.
First, check the oil level?!I'd change the switch, if it still does it then be worried something is up with the pump or oil system