Seeing "The sender object is currently not sending commands now. Command not sent" in JON agent log

Issue

• One of the agents/platform are offline in the JON console. I restarted the agent and can see a few errors in the agent log:

java.lang.IllegalStateException: The sender object is currently not sending commands now. Command not sent: [Command: type=[identify]; cmd-in-response=[false]; config=[{}]; params=[null]]
        at org.rhq.enterprise.communications.command.client.ClientCommandSender.sendSynch(ClientCommandSender.java:631)
        at org.rhq.enterprise.agent.promptcmd.IdentifyPromptCommand.execute(IdentifyPromptCommand.java:69)
        at org.rhq.enterprise.agent.AgentMain.executePromptCommand(AgentMain.java:2860)
        at org.rhq.enterprise.agent.AgentMain$5.run(AgentMain.java:2768)
        at java.lang.Thread.run(Thread.java:736)

Followed by these errors:

2013-02-20 06:27:28,601 DEBUG [RHQ Server Polling Thread] (enterprise.communications.command.client.JBossRemotingRemoteCommunicator)- {CommandService.remote-pojo-execute-not-permitted}Command not permitted - server reached its limit of concurrent invocations [Command: type=[remotepojo]; cmd-in-response=[false]; config=[{rhq.agent-name=example.com, rhq.externalizable-strategy=AGENT, rhq.security-token=UqyeOglqK66bWiWp2yZL32vgUV85iYEN3MLF62fvt7fBqv9RbUJPyAYQPlMG+YPTC0I=}]; params=[{invocation=NameBasedInvocation[connectAgent], targetInterfaceName=org.rhq.core.clientapi.server.core.CoreServerService}]]. Retry in [15,000]ms
2013-02-20 06:27:43,616 DEBUG [RHQ Server Polling Thread] (enterprise.communications.command.client.JBossRemotingRemoteCommunicator)- {CommandService.remote-pojo-execute-not-permitted}Command not permitted - server reached its limit of concurrent invocations [Command: type=[remotepojo]; cmd-in-response=[false]; config=[{rhq.agent-name=example.com, rhq.externalizable-strategy=AGENT, rhq.security-token=UqyeOglqK66bWiWp2yZL32vgUV85iYEN3MLF62fvt7fBqv9RbUJPyAYQPlMG+YPTC0I=}]; params=[{invocation=NameBasedInvocation[connectAgent], targetInterfaceName=org.rhq.core.clientapi.server.core.CoreServerService}]]. Retry in [15,000]ms