No, it's called natural behavior (or that's the term I just thought of now). The web is all about links, you see—links that mean something to the site owners. It's meaningful, useful and appropriate for a web designer to link to work that's been done, and it's fair enough (though some people don't like the practice) to put a link on the client's site to the web designer. This is all natural human behavior.
Google is not out to punish normal human behavior, but to slap down those who are trying to game the system for their own advantage. There is a big difference between those two things. The danger of thinking too hard about SEO is that you forget about the real world.