Infernalist Minion Revive Timer

Is there a bug with reviving minions or do i only feel it wrong?
If I have 17 snipers with 6 seconds revive time and 1 sniper dies after the next one dies too, within the 6 seconds, the reviving timer start from 6 seconds again.
So when they start to die, i sometimes have only 1 revive in about 1,5 minutes and this starts mostly when i have no sniper left to die and reset the timer.