I got the MI6 pin pointer and am really enjoying how it works, but I have a question. While I'm using the pin pointer I've noticed a recurring sound. It sounds like a "low charge" signal, but when I turn the pin pointer on, I get 2 light flashes indicating 60% charge. I've looked at the paperwork that came with the pin pointer, but I don't see any info about any indicator sound. Anyone else notice this sound?