Earlier last month my 2011 Hybrid suffered the same failure. For a couple of months I had been receiving an intermittent CEL, which would last a couple of days and then disappear. The dealership could not find any stored codes, so could not do anything. This was before my 60,0000 miles was up, and before my 5y of ownership. Eventually, a couple of hundred miles after my 60,000m was up, the CEL returned, so I went directly to the dealership (on a Saturday afternoon), left the engine running, and asked the Service Manager to verify my problem. They were too busy then to check codes, so returned Monday and was given a loaner. Diagnosis was air flap failure, but because I had repeatedly had CEL before my warranty expired, they replaced under Warranty. At the same time, I had an issue with a squeal that was associated with the engine running, not in EV mode. Again reported before, not diagnosed, but confirmed by Service Manager at the same time as CEL. Main belt tensioner pulley was diagnosed and replaced under Warranty, just paying for cost of new belt. Had loaner for two days while problems fixed.
So, if air flap problem is diagnosed before 5y/60,000m warranty expires, it will be fixed under warranty, but normally not otherwise. The bill was $1000 plus for the warranty claim.