Yeah, no one knows for sure. These sets haven't been out long enough to say otherwise. However, chances are good the TV won't have any issues in the first year. Plenty of people here have owned an OLED screen for more than a year with no issues.
When I look at OLED in other tech - like phones, I will say my Samsung Galaxy Nexus phone developed burn-in from the bottom taskbar after 3 years. That said, my phone displayed more of the same colors throughout daily use than a TV would, so it's hard to say what kind of impact that has on aging. It was also one of the first phones with an OLED screen, so I'm sure the tech has improved since then.