random search errors from one node of three on a previously working cluster

Hi,

I'm getting some random errors that started happening today. This is
one error:-

{"error":"ReduceSearchPhaseException[Failed to execute phase [fetch],
[reduce] ]; nested: ArrayIndexOutOfBoundsException[1]; ","status":500}

and this is another:-

{"error":"ReduceSearchPhaseException[Failed to execute phase [fetch],
[reduce] ; shardFailures {SearchContextMissingException[No search
context found for id [36813]]}{RemoteTransportException[[Aardwolf]
[inet[/10.206.38.97:9300]][search/phase/fetch/id]]; nested:
SearchContextMissingException[No search context found for id
[55197]]; }]; nested: IndexOutOfBoundsException[index (0) must be less
than size (0)]; ","status":500}

I am load testing my cluster by sending pseudo-random generated search
requests. I can take the search requests that fail, and replay them
manually and they work. Strange, as this test was working for the past
few days....  I have found exceptions in my logs on only one node, I
have copied them here:-

https://gist.github.com/1066838

Any ideas what could be going wrong? Shall I raise a bug?

cheers

Ian