I have been turning off both my GraverSmith and my compressor and draining it when not in use. However, last night I was reading the manual and I found this passage. The funny thing is I don't remember ever hearing a pop and hiss so when I went down to engrave today I tried it out while I was paying attention. No pop and hiss. I left the compressor on and didn't bleed it, the system leaked air when I turned off the GraverSmith and the compressor cycled. I'm confused, am I missing something?