2 ignition module failures - Coinicidence??

[Kudzupatch]

My GM module failed about 3 months ago on a trip in the mountains. Had to have it towed and someone else replace it.

Yesterday the aftermarket module they sold me failed on after 3-4 months. I was going to replace that one with a GM and keep it as spare because I know the reputation of the aftermarket parts but forgot about it.

Here is the thing that puzzles me. BOTH failed while coasting down a grade with my Suburban dropped down in 3rd to keep the speed down. They were both installed properly with the thermal goo in place. Maybe it is coincidence but it seems odd to me that they both failed in the same circumstance. I can't see any reason this would cause it but it leaves me scratching my head. Anyone else ran into this?