Where are you located?
If you open your footage with MediaInfo on one of your clips, what does it say?
I tried this on one example, and it read:
Notice it says: UTC, and the time is about 17:59.
The Date/Time title in FCP X, gives:
So, it SEEMS there is an error!
But then when I look closely - note that I'm in Portugal, and in September DST is in effect, so that is the exact time the clip was recorded.
Portugal is in the GMT timezone, for which the time agrees with UTC; when DST is in effect, an hour is added, so... all is correct, over here.
Could it be that the same is happening to you?