I know what you mean, MnM! I sometimes dread turning on the game for the same reason. I've been playing the game since it was released, and have seen many generations come and go, but have never really got over being affected by the loss of a peep. The first time hits even harder.

As Lyssaria said, 60 is a good age for a peep in the first generation, so they have lived a full (electronic) life.
Although I've said this before, it is worth repeating: the way the game handles the passing of the peeps is excellently done; it is dignified but not mawkish. Congratulations, LDW, on an excellent solution to what could be a real problem.