:)

Yup I do the same thing. A little Dawn with water and shake it up and spray it on. Works great!

Yes, dish washing detergent is great for leak detection. My Huben PCP has once developed a slow leak reducing the pressure by just 2 bars per day. It was successfully detected by using the stuff : 

https://www.youtube.com/watch?v=76XD9IHQjOU

So was this leak something you could hear or was it just noticing a drop in pressure at the gauge?

Dish washing liquid detergent works great and does bubble good when a leak is present. But BE AWARE that it is corrosive and should be COMPLETELY cleaned off to prevent corrosion. Home repair warehouses ( Home Depot, Menards, etc ) carry the non corrosive solution in the gas pipe dept. and is used for gas pipe leak detection. Do NOT buy from LOWES, they are ridiculously expensive. I have never seen the leak detector solution in a auto parts store.