Is this an allergic reaction to a bandaid?

I had a growth removed and biopsied from my leg on Wednesday. I used a different brand bandaid today and now my leg is red where the bandaid was attached. I’ve had the wound airing out for six hours and it’s still red.

Here’s a pic. http://imgur.com/PchwYIY

Is that just irritation or an allergic reaction?

I’m not worried, just curious.