"backfill exceeded limit' error for Q3 array indexing tests

test https://github.com/couchbase/perfrunner/blob/master/tests/n1ql/n1ql_thr_array_indexing_Q3_20M_between_gsi_ok.test

http://perf.jenkins.couchbase.com/job/hades/3346/console

As John Liang suggested I set Q3 mutation rate to 360/s

When I reviewed some traffic via ngrep on the query host I see errors for almost all queries like:
T 172.23.100.55:8093 -> 172.23.100.44:54763 [AP]
HTTP/1.1 200 OK.
Content-Length: 615.
Content-Type: application/json; version=1.0.0.
Date: Mon, 28 Mar 2016 14:13:16 GMT.
.
{
"requestID": "b1883ca8-eed4-46c9-860f-7819a26f4be6",
"signature":

{ "_name": "json", "_street": "json" }

,
"results": [
],
"errors": [

{ "code": 5000, "msg": "\"b1883ca8-eed4-46c9-860f-7819a26f4be6\" backfill exceeded limit 5120, 5214 - cause: \"b1883ca8-eed4-46c9-860f-7819a26f4be6\" backfill exceeded limit 5120, 5214" }

],
"status": "errors",
"metrics":

{ "elapsedTime": "664.371819ms", "executionTime": "664.113983ms", "resultCount": 0, "resultSize": 0, "errorCount": 1 }

}