Gluster users - May 2015 - new to gluster - s this strange output from "volume top gv0 read-perf"

I have a list of 20-30 files when i do a volume top gv0 read-perf - likeMBps
Filename??????????????????????????????????????? Time?????????????????????
==== ========??????????????????????????????????????? ====????????????????????? 
?? 0 ...tPortLevelData-2041366-20150529125006122.xml 2015-05-29 17:50:14.917153
?? 0 ...etAcctStatData-2041362-20150529124927384.xml 2015-05-29 17:49:33.624333
?? 0 ...etAcctStatData-2041361-20150529124843115.xml 2015-05-29 17:48:59.21495 
?? 0 ...etAcctStatData-2041360-20150529124753226.xml 2015-05-29
17:48:08.176853?Now they seem to roll off the list after an hour or so. But be -
just wondering?a) what the heck is that about??and ?b) should I even worry about
it??
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