How much is considered Bulk Downloading?

Hello, I’m developing an Android application that uses OpenStreetMaps (powered by osmdroid library), and must have the ability to display the city in which the user currently is in, in offline mode.

I’ve read the Tile Usage Policy and I know that Bulk Donwloading is strongly discouraged, but as the region I need is not to big, and the zoom level doesn’t need to be too high, I’d like to know how many tiles (or how much size) is considered against the policy.

I ran a test application that gets an 20km x 20km area with zooms: 11, 12 & 13.
For all the 3 zooms, it needed 76 tiles, and 1.36 mb (is a city, and the average size per tile is 20kb)
I also made a rough estimate of how much would be need if adding zoom 14, and it would need around 400 tiles, and 8mb

Up to 13 zoom is acceptable for the up, and 14 zoom would be great

This operation would be performed only the first time the user run the application in that city (once the app downloads the tiles they are cached in the device).
The application is expected to be used by the general public. (is not an app for internal use)

So the question is, is this behavior against the the Tile Usage Policy?, may the app be blocked?

If the answer is yes (it is against the policy), could you tell me what alternatives I have?

Thanks in advance,
JML-

According to http://wiki.openstreetmap.org/wiki/Android , an alternative can be the http://wiki.openstreetmap.org/wiki/Mapsforge framework which is actively developed these days.

It has the advantage to NOT use tile graphics but one vector offline map.