Nah. .PST the way the .pst files work is that they increase in size as long as you continue to add to them.
Once you take away from they retain their size.
Depending on what version of outlook you are using you can fix this easily.
For Outlook 2000, right click the folder you wish to reduce in size. Click on properties. On the menu that is opened, click the 'Compact Now' button.
For Outlook 2003, click on File->Data File Management. Now on the menu that opens, push the 'Add' Button. Select whichever option applies to the folder you wish to reduce in size. Click the 'Ok' button, then navigate to your .PST file. Once found click it, and push the 'Ok' button.
Now you are back on the previous menu, and you will see your .pst folder listed in the list box. Select your .pst and then click the 'Settings' button.
From the menu that opens, push the 'Compact Now' button.