Ok so I'm driving home from work and I go to pass someone and from 50 to about 70 and let off the gas and I look down to see my temp gauge go up alittle and back down after a few seconds.I don't think this is normal so I check coolant levels and it looked fine to me. I get the low coolant light on when I first start the car for 3 or 4 seconds and I've put about half a bottle in and the level has seem to stayed. I checked the oil and nothing looks out of place. I'm going to get the car scanned tomorow to see if anything pops up but what should I look for? The car is due for an oil change anyway. Ideas?