In my opinion (for what that's worth), if your muscles are sore from the workout, you're retaining water and lactic acid. I think that's good. It means your workout was effective and you've torn those muscle tissues so they can repair themselves and make you stronger and leaner.
But from a P3 standpoint, it isn't good. In P3, you have to know whether or not you are stabilizing and if you are working out like that, you can't know. Technically, you should do a correction day. But if you choose to continue working out like that in P3, realizing that will mean you won't know what is a weight gain and what is a workout gain, maybe you want to give yourself a 1-2 lb buffer to account for the fluid in your muscles.