Originally Posted by After Shock Media

One reason for paperwork.

Now many seem to forget a designer litterally owns the design and copyright to what you paid them to make unless they sign over such rights to you.
Technically they can charge you for each alteration, if you decide to use the logo elsewhere or whatever. Hell they could have you stop using it all together I suppose.

Yes when we do designs for people we give them the psd when asked and also sign over full copyrights.