Are they pushing new growth? If so, you should begin to "harden them off" by gradually exposing them to air for ever longer periods of time. Too fast and they will die from drying out, too slow and they will die from "damping off".
If your dome is getting a lot of water on it after replacing it then dry the dome and replace it. You can also begin by propping up your dome by an inch for a few minutes. This is why I like the domes with the vent.