As per your question, actually Diarrhea
is called when a person passes stools more than 3 times a day and persistently. Caffeine(like in Tea, coffee, soda) may cause motility enhancement but passing stools for 2 times doesn't have to be worried about. Watery stools
or painful / bloody stools would bring up the actual attention. But in your case it could probably be because of workout and caffeine which increased your metabolism
and intestinal motility caused to pass stools.
Have a great health.