Embarrassed to say the least 🫠

At pre school pick up today I have been informed my child is spitting at the other children (absolutely not a behaviour I will tolerate)I apologised a bunch of times but I’m so embarrassed he’s done it in the first place, the only game we play at home where there’s remotely any spitting is in the bath when he sips the water to spit it out. Should I stop playing this game ? He doesn’t have the greatest communication yet but does have a great understanding. He also spat for the first time on the walk to pre school yesterday where he was reminded firmly that we don’t spit it’s dirty and we only spit in the bath or when brushing teeth and he didn’t do it again. How do I approach this and stop him from doing it as it’s not something he does at home.