Welcome to LQ
Not sure I follow... If you can see the messages in Squirrel at all, at any time, you should be able to see them when they are new? Do you mean they take a few to get to the actual INBOX? Or do you mean it doesn't show in the left pane that there are new messages? You can change how often it updates the left pane in your config, I've set mine to every 4 minutes ( a refresh basically occurs of just the left pane).
Could you clarify what you mean if what I've mentioned is not correct?