Ahh, the worry of poop!! my DD is 7 months and its still the number one topic! I think that its very normal, my LO would go after every feed in the beginning then it kind of chilled out a bit, although she still always pooped after her night feed until she was about 4 months, which was fun!!
I always thought she was just getting into some kind of rhythm and then a week later it would all change!
As long as the colour is good and shes wetting plenty of nappies then I wouldn't worry!!