Why is this hydrocolloid band aid pillowing out?

So, I have a wound on my leg and on my foot. I have a special band aid on each. They are waterproof, seals in moisture, and cushions the wound, and can be worn for up to 7 days at a time. I noticed the wound on my leg, the band aid is pillowing out. What does this mean? That wound is particularly sore. Does it mean there's just more weeping fluid coming out or why is it doing this?