How to prevent PrimeFaces poll from clearing FacesMessages?

I'm using PrimeFaces poll component to refresh some content.

<h:form id="formBsvtt">
  <p:messages autoUpdate="true" showDetail="false" />
  <p:outputPanel id="panelOut" layout="block">
    ...
    ... content to refresh
    ...
  </p:outputPanel>
  <p:panelGrid id="panelIn" layout="block">
    ...
    ... various input components with validation
    ...
  </p:panelGrid>
  <p:poll widgetVar="poll1" autoStart="true" global="false" interval="15" 
    partialSubmit="true" process="@this" update="panelOut"
    listener="#{myBean.myListener}">
  </p:poll>
</h:form>

As you can see I'm using messages with autoUpdate=true. My Problem is: In case of validation errors FacesMessages will be shown, but disappear not later than 15 seconds.

Is it possible to prevent poll from clearing FacesMessages without setting messages autoUpdate=false?

My web application is much bigger as code snippet specified above and my intention is not updating messages manually in each possible case!