I found a fun thread at HighRankings Forums that discusses what he calls "unintentional reciprocal links." What I find funny about that name is that, if you think about it, an unintentional reciprocal link, but definition, is a natural link.
I believe this person is worried that Google or a search engine might classify his site to be in a link scheme if the people who he linked to, links back to him. In many cases, the places we link to, will naturally link back.
How often do I link from here to Search Engine Land and from Search Engine Land back to here? Is that a reciprocal link? How often do I link to other search blogs, that link back to me?
It is just natural to have "unintentional reciprocal links," so don't sweat it.
In the thread, Jill Whalen, owner of High Rankings, added an other point about reciprocal links:
In that case, the original poster is under the false impression that a reciprocal links are penalized. Since they're not, there's nothing to worry about.
Forum discussion at HighRankings Forums.