A Google Webmaster Help thread asks a very interesting question. Should a webmaster consider submitting a reinclusion request if the site is still ranking well in Google?
The question seems obvious. Why would you bother submitting a reinclusion request when you are ranking well. But in this case, it is not so cut and dry. This webmaster received a notification from Google that they are hiding text. The notification came about a year ago, and they didn't really care so much back then. Now that they are boosting their web efforts and revamping their site, they have removed the hidden text. They believe they have good rankings, but they wonder if submitting a reinclusion request will improve their rankings in Google.
Googler, Wysz, suggested that they play it safe and submit a reinclusion request in any case. He said:
Over time it's possible that we detected a violation of the webmaster guidelines was removed, but as Autocrat said, it's probably best to play it safe and let us know that you've made changes to your site to fix previous violations. Don't worry about any downsides to requesting reconsideration. We don't bite. :)
Just be upfront about what you did, when you did it and what you changed. Google doesn't "bite," at least according to Wysz. I am sure many folks would argue with the bite phrase. :)
Now, if your site is nice and white, sparkling clean, I would also suggest submitting the request. I don't see how it can hurt, unless you are hiding something or you are unaware of something that is wrong on your site.
Forum discussion at Google Webmaster Help.