i had this problem too, along with some others. It seems to only effect the microdrives. So far, there isn't a fix for it other than running out of time and then starting a new recording.
I'm going to try some tests this week, right now i'm thinking if you shut off the mt, pull the microdrive out, restart the mt and then put the microdrive back in - the mt might reset so the remaining time is correct. hard to say tho.
looks like this might be something that someone should report to m-audio, but i haven't gotten around to it yet.