Makes sense, since you start single player with a pretty low health bar. The strange thing is that all multiplayer maps have the same (multiplayer) ego instead. And the EGO bar seems to take the EXP bar down with it.

The ego bar? I'm not sure. First time he shot me i think my health got critical, but i also remember tanking 2 hits.
64 said that it might be because the spawns are registered as single player campaign spawns.

Is it actually this low or is it just the UI?