I'd say that the behavior is obsessive and indicative of the cage being too small.In accordance with the current US minimum being 450 square inches,and the tank being a mere 360 square inches,I'm not surprised that you'd be seeing any obsessive behavior.I know a 20 long can seem big at first,but they're very small for a Syrian
For a quick and cheap fix,try a bin setup.2 105 qt Sterilite bins($12 each at Walmart),1 64 qt Sterilite bin($7 but Walmart exclusive for the size),zip ties,1/2 inch mesh,wire cutters,and a wood burning knife($13 at Walmart)would be all that you'd need,maybe with an extra bit of wood underneath the smallest bin keeping it in between to allow a smooth direct connection!You can do this gradually starting with one bin and then add on bins one at time to keep it as stress free as possible.