@Steve *******
There's nothing wrong with the 7 day stamp, it's not an overstay, it's a legitimate extension but the way it's worded may make some people freak out. Even the one year extensions contain threatening statements like "offenders will be prosecuted". No other country in the world to my knowledge makes such provocative remarks on a simple visa extension.
Other countries, rather than Thailand, may interpret the 7 day stamp in a negative way but purely due to the wording.