It happened on two different devices yesterday for me. I've had it before also. There is something in the pairing that causes it, I think. In one instance they made a trip start earlier, and the trip is proffered. But the date in VIPs is still the original (now wrong) date. If you go to the pilot's calendar and click on the trip it will show correctly.
When it crashes, I don't use FxCal to look at individual pairings for awhile, until the schedulers fix the error or the trip gets picked up.