The hood insert is bolted down, so maybe the nut just worked loose. Worst case, the adhesive holding the bolt to the back of the insert has failed, and you'll need to reglue it (JB Weld should work). Pull out the round plastic retainers that hold your underhood sound mat in place & remove it to get at the nuts that hold the hood insert. Note - the washer nozzles also have to be removed to take out the insert.