Burning oil?

Hello,

My car currently has 27k miles on, last serviced at 20k
miles. Last night I had the "check oil" light come on. I
checked the oil and it was at the minimum line on the
dipstick. I stopped it off at the dealer today and the service
advisor said this is "normal" to have to top off the oil after
about 7k miles??? This isn't the first time I've  dropped off
the car for the same issue. The last time it was at 14k
miles, same thing low light came on dropped off the car
and that time the advisor said it's NOT normal so they kept
the car for 3 days and ran tests to see if it was burning oil
so they concluded that since I didn't buy the car from them
they didn't know if it were topped off with the correct
amount of oil because it wasn't burning any oil. So my
question is it normal for an E350 to burn oil with only 27k
miles on it? Or is this advisor crazy? TIA!!!