Do me and my BF have too much PDA(public displays of affection), and if so, why should we stop?

My boyfriend and I tend to make out and touch each other a lot in public. It's not on purpose, we just do. Sometimes we will even have when we can (whether in public or not.) Is this too much PDA? How much is too much? My friends have told me it's a little uncomfortable, but why do they even watch? It's their choice. Please answer my question!