I have a SS with an exclamation point on its icon, what does that mean

With the introduction of Office 2007, macro enabled worksheets saved as .XLSM files show the exclamation point as part of the icon. This is not to show that it is an error or that it is dangerous, only to inform you that it contains macros. "Feature" or not well thought out placement of punctuation? Its completely normal, and everything is fine as long as you trust the document and/or created the document and macros yourself.