#30 tempfiles get deleted but not closed

From time to time my /tmp (which is a separate
partition for security reasons) fills without any files
accounting for it. I found out this is because of a
large tempfile created by ubh, then deleted but not
closed properly so it lingers around for a while.
With lsof, this looks like:

lsof /tmp
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
ubh 28077 koos 4u REG 8,9 30019584 20
/tmp/tmpf5Vjk8b (deleted)

ubh does not seem affected (I see no errors or
misdecoded files), it just closes the filehandle after
a while which releases the space.