3 of these just failed

Initially I was very pleased with these 5 chip 1/2 Watt LEDs I acquired from ebay.

For testing I ordered 10pcs of the warm-white type (100,000 mcd @ 100mA), which are shown here, and 10 pcs of neutral/cool-white (120,000 mcd @ 100mA). NONE of the latter have failed so far.

I use constant current LED drivers, therefore it shouldn't have been over-current that has killed them. 3 in a row.

Now will I use these, or search for equivalent/better SMD types?