I had a moderate bruise and now and noticing a hard lump under my skin where the bruise is going away. should i be concerned that its a blood clot?

It is but it isn't: 'blood clots' that are dangerous are those within blood vessels; these can travel thru the bloodstream and block blood flow. Blood is supposed to clot outside blood vessels--that actually stops bleeding after trauma, such as your black-and-blue mark. Your hard spot is blood outside any blood vessel and is harmless; your body will absorb this slowly over the next few weeks.

Sounds normal: This sounds fairly normal. Usually after even moderate soft tissue injuries there can be a period when the area feels hard. Usually this peaks around 3-4 wks after the injury and then goes down. Keep an eye on the area to make sure it's improving and that you have no other symptoms. It should return to normal but can take some time.