i just dropped too much (4 tsp - with one of those tsp measuring device) into ~9oz 190F water and also forgot it about 5 minutes... came out rather strong and bitter/strongly astringent, somewhat unpleasant to drink :P
took a pinch of those wet leaves, about 1 tsp, about 4oz water, and left about 2 minutes, taste came out better, but mild, with a touch of sweetness...