I had a conversation with Max Testa about that a number of years ago when I was living in California and training with him. He said many times these sorts of issues run sub-clinically with no major symptoms. Then after a stressor of some sort (hard training, not enough sleep, etc.) it comes out as a cold, flu, or other thing.

He told me it is not worth it to push through illness. It is better to take a few days easy then to push through it and get sicker. That would cause you to take more time off.

Since it is a recovery week, a few easy days won't hurt.