My 2007 Impala shudders and hesitates intermittently for 1-2 secs on acceleration, oftentimes going for weeks at a time without incident. From what i can find the selenoid valve may be clogged or it may be related to article #06-07-30-023B: 4T65E Transmission 1-2 Shift Shudder at Light to Moderate Acceleration. Would either of these repairs be covered under the warranty?