Gmail Quirk: First check... 'Check now' ...and next interval check

I'll just note that, in Chrome, when I first start my browser and X-Notifier (v3 or v4) first checks for new mail... it only checks my primary Gmail and leaves my second and third accounts unchecked (as well as my accounts).  All my other accounts are checked fine.  
HOWEVER... once the check interval time elapses, ALL my accounts are checked from then on (including Gmail and accounts).  I don't know why, and it's not a major problem for me to waste time fussing over.
NOTE:  I can also click 'Check now' to force a check which does check all my accounts, if I just can't wait for the mail check interval. (Default is 10 minutes.  Any faster and your mail server may resist responding. Checking more frequently than 10 or 15 minutes is called 'hammering' the server.)
-- So... perhaps some of you are experiencing this 'first check' anomaly... and assuming they're never checked. I don't know... I just thought I'd mention it.  To test your mail for this, just click 'Check now' to see if it works... if so, subsequent interval checks will also work, most likely.
As for Firefox... all my accounts are checked from first start... no anomaly.