Quotes Change Color when passed price guarantee

I think it would be helpful to have quotes turn red (or another color) after 30 days of creation (or any custom time guarantee). Our prices are guaranteed for 30 days and then once the 30 days have passed, the price is no longer guaranteed to be the same and it would need a new quote. If the quotes that are at the 30 day mark or more turned a different color, it would remind me to go through and delete those from the system