I will say that this issue appears even on my phone....and I'm rooted running Ginger Villian 2.8...and have reflashed it a number of times.
At first I thought it was the a2sd+ scripting not working, but even on this fresh install with the script working perfect, I was still losing a little ever other day...I mean yea I install apps, but not as many as I did and I am very careful in noting how much space I had before and after said app install and since they have been running..
It has since stopped taking any extra space...but I don't know why it was or even what caused it to stop...just one of those weird issues..oh and I am running a cache cleaner, but an automated one that I don't have to physically click every few hours or days cos sometimes my cache REALLY take a beating at times...had 45mb in there the other day (but thats unrelated to the memory drain from before)