Clothes dryers can make thumping noises for a variety of reasons. If you have a similarly mysterious sound coming from your dryer there are a few things to immediately check for before you call a professional.
Thoroughly check the inside of the dryer for any foreign objects with hard surfaces. Sometimes items that fall out of pockets become stuck inside a dryer and make thumping noises.
Check for level
Make sure the dryer is level. A dryer that is out of level may not rotate properly. Banging or thumping noises from unleveled dryers are common, particularly if the dryer is resting against another metal object such as a washer.
If the thumping noises are present only for the first few minutes of the drying cycle the likely culprit is rollers. If the rollers are warped they will need to be replaced and a professional should be called in to help.