Diarrhea and Flea Treatment

Is it normal for a cat to have diarrhoea after having flea treatment? I used Frontline Combo on Moofie last week and a day later he had diarrhoea - not bad, just messy! Nothing else had changed, same food, water, timings although I can't say if he had eaten a fly etc :smile:

He has just started going outside and it is the first time I have used any treatment on him. The worming treatment was fine.

I was just wondering if anyone else had experienced this and whether I should change the flea treatment?