L.M.
Try to watch him closely and see if he's doing anything to alert you just before he starts running to the bathroom. My sons still keep playing until it is an emergency, so I have trained myself to notice if they start squeezing their legs together. They both do it and try to wait so they won't have to drop what they're doing to go to the potty. My younger son still has accidents occasionally because of this, but my older one always makes it, he just ends up running if I don't notice his body language fast enough. I think they all have to be reminded to go for a while after potty training, longer depending on the kid.