to neutralize the rust take a small grinder or some corse sand paper and sand/grind the rust off. then take an etching primer and put it on the bare metal. then brush touch it with ur touch up paint. this wont be a perminant fix but will be ok for a while. my 2005 hood is checked on mine as well. it could be just the age or the sun attached it, the paint could be to thick and overtime cracked, the type of paint, many of things. my gues it type of paint.