I've seen bubbles like that on live rock if there's some algae a' brewin. I blow the rocks with a turkey baster before doing a water change to make sure there aren't any sediments building, and since using RO
water, I haven't had a problem with algae and bubbles like that. I also adjusted the flow a little in my tank to make sure there weren't any dead spots where debris could accumulate in the rocks and give algae a place to grow. It could just have been air inside the rock that got disturbed when you moved them. Try a turkey baster or toothbrush (ideally not the one you use yourself
) to break the bubbles, and see if it forms again over 24-48 hours.