ACS Query that has worked for months... now returns nothing... hmmmm

So, I have an app that shows a 'pop up announcement image' at app startup, based on the date. For example, I have an image stored in ACS with a startDate of Aug 25 and an endDate of Sept 30th, so it will pop up any time the app is opened between those dates... all of a sudden this week, the query is not returning any values.

Here is an example,

Photo Object Custom Fields

city_id 1
announcement    true
startDate   "2013-08-25T00:00:00-1200"
endDate "2013-09-30T00:00:00-1200"

The query that I run against ACS is as follows:

https://api.cloud.appcelerator.com/v1/photos/query.json?key=XXXACS_APP_KEYXXX&page=1&per_page=20&where={"announcement":true,"city_id":1,"startDate":{"$lte":"2013-09-11T00:00:00-0700"},"endDate":{"$gte":"2013-09-11T00:00:00-0700"}}

If I remove the date modifiers, the query returns data, but not if I include the dates... I HAVE NOT CHANGED ANY CODE in the last weeks, so it seems like something on the ACS side...

Any ideas what might be going on?

Ray Belisle