Mark's idea is a good one; if you create a temp Smart List and broaden the criteria to customers with a closed-won opportunity and an end date with a timeframe of 60-90 days, you can see if anyone should have qualified on Sunday or Monday. Also, doesn't hurt to check the logs in your batch campaign to see if there has been any recent activity (if you haven't already).
Finally, another good idea is to use yourself as a test lead (again, referring to Mark's suggestion). You would create a contact in Salesforce with your email address as your own, and then open a test opportunity for that contact. Update it to Closed Won, set the end date accordingly, and see if your test contact appears as a qualified member on the Schedule tab of your batch campaign. It should say "Set to affect around 1 existing leads (may change over time)." Note that it can take around 5 minutes for your contact to auto-sync to Marketo.