The carrot is a start of line Definition for the expression, what may also be missing is the fact that some Keys do not have a full 8 digit hex entry at the end of them. If you find your regex's completely hit or miss compare it to another device not reporting a conflict, and validate.
Next, for those with remaining issues, try: [A-Fa-f0-9]+[ \t\r\n\v\f]*
You can name it "Ignoring End Hex" or w/e but that is specifically what it is written to ignore. Interestingly enough if one part of the entire block IE, ! to ! of that portion of the config doesn't have a regex excluding the pattern the entire block will be highlighted as a diff. This is how it is parsed on the back end, it is not actually a line by line comparison which is why the regex's include end of line characters \r\n etc.