First of all, It has nothing to do with you ACTUAL graduation. its mere symbolism that your memory or subconscious uses to capture the emotions you experienced an felt maybe approaching your graduation that it is trying to apply to another event in your life.
Maybe because the event has not been fully identified by you yet, it continues to manifest itself in a form that your mind and body knows it has experienced before.
Something may be either approaching that has you a tad nervous and maybe giving you a heads up to have your ducks in a row before the date comes. it can be telling you something as simple as having all your papers and pre-requisites ready for a job your applying for. Or make sure to check all loose ends before the deal on buying a new home reaches the closing date.
It just seems to be about preparation and being ready for something that is coming your way.