Download error with sale priced apps?

[joeswife5807]

I have a few app tracking apps on my ipad 2 that tell you when something goes on sale. For the past week or so I have been experiencing difficulty downloading some of the apps. Ive tried both through the tracking app and directly through the app store. I keep getting a message that says "this app is currently being modified. Try again later". It doesnt happen with every on sale app. It is random. Some I was able to download with no problem. The ones I got the error message for I had to try for a day or so and multiple times per day to actually get the app. There is one Im still trying for. Im pretty sure the problem is not with my device as everything else works perfectly. Ive heard it could be the itunes server. I contacted both them and the app creator and I couldnt get a definitive answer from either. They both said basically keep trying. Has anyone else been experiencing this? Does anyone know what is causing it?