I overheard someone talking with one of the PTs while I was warming up for therapy a couple of months ago. They were talking about overdoing one day but feeling fine the next, and the PT said that was the important part -- that the joint recovered overnight.
That conversation made sense to me, and I'm going to agree with PumpkIn that the swelling you're experiencing is normal for your knee in your situation. I would take that it going away overnight is a positive sign, and I don't think it will interfere with healing in the long-term recovery of your knee. Short-term, of course, it's absolutely no fun at all.