I think it's always good to double check the device to make sure everything is functioning properly. I have found that since I have gotten the hang of the placements and how much saline to use that I don't really "feel" anything either during the treatments. If something is wrong the device beeps at me (this happened a number of times in the beginning when I was still finding my way). Do you think you might have done anything differently like used more saline or had the straps adjusted differently? As said...you could just be getting used to it. Joydee's suggestion about calling the manufacturer is a good one too if you are worried. It's one of those things where not being in your shoes no one else can really judge because any of these things are possible.