wal error 'already been removed' on promotion

hello!

i promoted successfully for my needs a slave to new master (peeled off for
new cluster).

However, i get non-fatal error that indicates xlog changover was not clean.
At this point, i just want to resolve & move on - i've done successful base
backup before & after & verified the new timeline logs are good. But how
to get rid of it?

here's the sequence of events -

00000003000000BA00000066.lzo old timeline id; wal log saved in old
location.

on promotion and new wal logging location, this sequence order:

00000003000000BA000000B6.lzo
00000004.history.lzo
00000004000000BA000000B6.lzo

however the error that won't go away is based on new timeline:

2017-02-10 23:44:45.777 GMT 643 10.188.0.74(46096) 14/0 ERROR: requested
WAL segment 00000004000000BA00000066 has already been removed

it seems likely the segment was in play at the moment i promoted, but did
not expect the error. Restarting does not make error go away.

This is pg 9.3

Advice?

thanks in advance!

-gleeco