We notice the same thing here.  I will be interesed to know what the EVO people say about this and which report they say to trust

I use average costing.  My differences seem to be extreme lately- last 3-6 months.  But again if I do month end vale at month end, its within reason.  The differnece shows up in raw inventory not finished goods.  
 
When I compare the average costs between say today and 2/1/10.  They are the same which I guess makes sense since they are using today's average cost.  I did not keep a print out of 2/1/10 actually ran on 2/1/10 to compare.
 
Did something change in updates maybe?  Because I know there were many times in the past (say last year) that I did not look at month end inventory at actual month end but later into the next month and didn't have big differences.  There has always been some difference just not hug like now. However I will note that our inventory levels this year have increased a great deal compared to last year.
 
Hmmmmm.