There is a section in SkinStudio:
Window Borders/Titlebar Text/Titlebar Text Background
You can define/set a background image for your text there which should expand/contract with the text up to limits you set. I don't believe this works with perpixel (transparent) Titlebar images, however; I think only regular non-perpixel borders support this feature (I could be wrong about that since I haven't spent time working with perpixel borders).
If my suggestion doesn't address your issue, posting a screenshot might be of some help.
