Help Why After, before app uninstall phone memory not same?

[Andima]

Hi!
I installed 38MB internal memory usage app in my Xperia mini. Before install this app, my internal memory is 280MB. But after i uninstall my memory is 278MB. That mean there is a 2MB different. After that i clean phone using "Remove history" app, it only remove 0.2MB or similar amount. I only install this app. So why it's wrong?
That mean if i uninstall app, its some files are remain on my phone memory? If so how do i completely uninstall applications.

 

[Josh-SonyXperia]

Just to confirm, was the app installed on the phone memory or on the SD card of the phone? And as far as I know once you uninstall the app from the phone it is completely removed unless some additional content was downloaded and installed to the SD in which case you'd have to remove it manually.