SP 120 bubbles and cracking panel

I recently had an SP 120 panel start to bubble and crack while collecting sun. It was perfectly clean and fine when I set it up and about 15 minutes in I noticed the problem. Clear sunny south Florida morning about 9:30 am temp was around 70. This has happened to me once before almost to the day one year ago. That time I didn’t catch it until it started to flame up. I have notified support and they are replacing it. I take care of my panels, clean and store them appropriately. They look almost new. Does anyone have any idea what could cause this problem?

@Fig Glad to know that the support department is helping you to replace your solar panels.
Hot spots, cracks and yellowing in solar panels during use can cause a drop in power production.
Hot spots, which are localised high temperatures within the module, can be caused by a number of factors. It can be due to poor installation, maintenance or shading by leaves, bird droppings etc. Shaded areas of the cells can start to heat up or even burn.

Thank you for taking the time to answer my question. I will keep an eye out for hot spots but having to stand watch for bird droppings while using my panels doesn’t seem practical. :) Again thanks for your help.