In my case, I was off the bike and trainer for over a week, and I was on the backside of the flu. I think it actually helped finish it off.
I know of zero medical or physiologic basis to accept the premise that you can "finish off" an illness by racing. While in your case it might not have negatively impacted you, it's pretty much a stretch to accept that it positively affected you beyond a placebo effect.
Not to say that the placebo effect isn't something to be reckoned with from time to time.