Is there any more data with the log like the actual index number?
We can see all the ifl setup on the device this way
show interfaces extensive | match ifIndex
I also did a search in the PR database (Problem Reports - Junos bugs) and I don't see this listed but your version of Junos was not availalbe as a filter either. This is starting to feel like a bug.
prsearch.juniper.net/InfoCenter/index?page=prsearch