It's
expected if something causes fseventsd to lose track of events and thus
reset its history. The main reasons fseventsd can lose track of events
is if the system crashes or reboots unexpectedly. An event overrun or
fseventsd itself crashing can also cause it but that's pretty rare. The
other thing that can cause it is if a volume is modified by someone
other than an fseventsd capable system. In that case we don't know what
changed and thus have to toss the history and generate a new volume
uuid.