Dave Horvath Writes:
"Early in the game, Michael can be found around Sanctuary quite easily, and rather frequently. Story spoilers aside, something happens and Sanctuary changes. After that change, the frequency in which Michael appears for every load into the town drops significantly. I’ve personally gone through and have seen him every 5 loads, but to the same effect, as was the case last night, I’ve loaded the map repeatedly for over an hour and he didn’t appear at all. The loot that he gives you, matched to your level, does warrant some extra time trying to find him over and over again."