google map cache always trashing itself

I have the google map 5.1 and since i have my sgs2, the cache of the map is always trashing itself, one day i scroll maximum to get the bigger cache to avoid data when go out of home, but next day i power on the phone and go check the cache and it as dropped ex (one day at 43 mo next day 6 mo..) what the f

 

so as I can see here everybody has thier google map data cache stable?..