We have built a cross platform app using PhoneGap and Sencha Touch, from which we use YQL query.
We have a quotes screen which we want to refresh every five minutes for the same list of Scripts. We do not use any cachebusting techniques to get fresh value every 5 minutes, but are expecting that the YQL cache would refresh at regular interval within 5 minutes and so we would get fresh quotes. 
But here is what we are observing, we only get the new quotes after 15 or 20 minutes mostly. For the initial few times we do get refreshed values for the first few (2 or 3) calls, but after that the prices refresh only in 15 - 20 minutes. 
To test out a different scenario, we wrote a Java test program to run the same query from the console and put it into a loop to run every 5 minutes and observed that we did get fresh values every 5 minutes. In our actual program however, we use Javascript to make the required calls eery 5 minutes. 

Can someone please help what is wrong here.

Thanks