The size of the working set here is very small and this is not likely a real problem. See the update on this blog post that states this could happen on a system with no databases and no activity:

http://blogs.msdn.com/b/psssql/archive/2009/05/12/sql-server-reports-working-set-trim-warning-message-during-early-startup-phase.aspx

If you see a working set trim of a larger working set with activity then it would be a problem. I'd also recommend reading this article on LPIM:

https://www.simple-talk.com/sql/database-administration/great-sql-server-debates-lock-pages-in-memory/[/url]

I take the stance that an ounce of prevention is worth more than a pound of cure since this would prevent problems if you setup your instance correctly.