LED light strand mystery

[darkoshi]

Before xmas last year, I put up a new multi-colored xmas light strand at Qiao's house. It's the simple kind; it doesn't flash or blink or change colors. A few weeks ago, I noticed that 2 of the bulbs, fairly close to the end... the 9th and 10th ones from the plug, to be exact... were out. Every now and then, I see those same 2 bulbs turn back on for a while, or flicker in unison as if they are on a different circuit than all the other bulbs. The other 98 bulbs on the strand stay on steady. The strand itself is motionless the whole time. What could cause just 2 of the bulbs to flicker like that?