I got the same sort of line
I got the same sort of line from the dealer and it would seem this is their standard line, but I pushed and pushed and in the end they fixed it under warranty by putting in new engine rings. Although it would seem that mine was using more oil than yours. Mine went from the full mark to the add mark, in about 1700 miles. It had been using varying amounts of oil since I bought it new. It used more when I went on longer trips, such as a family holiday trip, where we were driving for longer periods at higher speeds. I would keep a close eye on it, and if it continues to use too much oil or is of concern, take it to the dealer for oil consumption tests. They will top up the oil and keep a record of how much they add, I would suggest that you keep a record too. That's what I did, they put me through that for a year, before I got any action out of them. And then I had to walk in put the keys on the counter, tell them I did not want the car back until they fixed it, and just walk out. At least they knew I was serious about it. The new engine rings were only fitted last week so I don't know if it has fixed the problem yet, but I am back off to the dealer today, because since they fixed it, there is a rattle / knock in the engine for a few seconds when I start it after it has been sitting for a few hours. Disappointing that Subaru seem to be trying to sweep this oil consumption problem under the carpet