No, unless you hear your baby keep pooping watery poop non stop. e.g watery poonami at 8am, watery poonami at 8.10am, watery poonami at 8.20am, watery poonami at 8.30am. You should feel as though there is something very wrong with the frequency, then it's diarrhea. Pooping just once a day is not diarrhea. 3 times is also not likely.
Diarrhoea means poop right after milk and soil diaper at least 6-7 times, watery and butt start to have nappy rash. If baby poop once a day or 2-3 times a day and as long as no blood, not watery poop it is okay. It should smooth poop at least.