I agree with PlatinumBoy , once you get your muscles warmed up you will be alright, just make sure you have a good stretch and proper warm up. Sometimes the best times to train are when you really ache from a hard session the night before, its just acid building up in your muscles.

If I didnt go training everytime I ached I would hardly be at the gym!!
The only time I would say not to train is if you have an injury, thats when you have to listen to your body and rest.