FileGrowth changes after the execution of DBCC SHRINKDATABASE

Using sp_helpfile to my database (SQL Server 2005,SP1) I get the following results

Data File size=5103616 KB, maxsize=Unlimited, growth=204800 KB

Log File size=504 KB, maxsize=Unlimited, growth=204800 KB

I execute a maintenance plan having only a Shrink Database Task. This task produces the following t-sql

USE [myDB]
GO
DBCC SHRINKDATABASE(N'myDB', 10, TRUNCATEONLY)

Now, executing sp_helpfile I get the same result but if i restart sql server I realize that the Data file's growth changes to growth=25600% (there is no other action or job using my Database)

What could cause this?

Thanks in advance

I've just learned this is a known bug.
http://connect.microsoft.com/SQLServer/feedback/ViewFeedback.aspx?FeedbackID=127177