Illness affected performance - but not that much?
I'd leave it out. This certainly doesn't sound like a bad semester that needs to be explained away. Being able to do well under adverse health conditions isn't really something you want to use as a selling point. Stick to what you did, not what you think you could have done.

If you mention it, there's a risk that someone on the admission committee will wonder if your illness is going to come back, maybe worse this time, and affect your work in grad school. They should not consider that, but people are human, so they might.

Congratulations, and glad you're feeling better.