My cat ingested a tiny bit of dove soap?

So my kittens LOVE to lick up the water in the bathtub after we shower. Well the water was dripping from the shower head afterward and a little of the soap right underneath the shower head) dripped onto the drain, and there they were, licking it up. One of my little guys is kind of trying to burp it up i think. If he is acting otherwise normally and is not vomiting, I ume that he didn't ingest enough soap to really hurt him. Any ideas?