Congrats! They're good at hiding.
I just assumed that there was only one type Hornworm that ate tomatoes but I did some googling and mine have a reddish tail so I think they're actually Tobacco Hornworms.

I found 2 more, a couple of days later. No frass, so I guess they had also been molting and inactive. I moved all 5 cats to the peppers to finish, then brought them inside, Friday. I did not have to wait long before they all quit eating so I gave them a fresh box of moist peat medium and all but two, began burrowing immediately. Only one had changed color, though. Two hours later, the last cat was under the peat. I will diapause these pupae.