Saw this on the 920 Owners Group on Facebook yesterday. They don't look to be a problem based upon the photos. If you have a set of calipers could you measure the width and thickness, in millimeters, without compressing the wrapper and post the dimension here? I could compare them against mine to establish differences. Thanks.
I have many aircraft and in the RC plane world those batteries have defective cells. They should be replaced. Tips to Avoid a Swollen Battery
Proper charging – Make sure you charge your battery properly using a quality battery charger. For safety, make sure you put your batteries in a lipo bag while charging. If you don’t have a lipo bag, I highly recommend you buy one. For around $10, you can insure that if something does go wrong at will at least be contained.
Don’t over-discharge – Make sure you stop using your battery before the voltage gets to the minimum cut-off voltage.
Heat kills batteries – Don’t use batteries or charge batteries when they are warm. After you’re done using them, give them a little time to cool off before you charge them. And after you are done charging them, give them a little time before you use them.
Proper storage – Do not store your batteries in a hot location. (For example, don’t keep them in the trunk of your car during in the summer.) Store lipo’s at the proper storage voltage. The article I linked to above showed that swelling increased significantly after only 4 hours of storage when batteries were at a state of charge above 80%.