soreness is not a sign of a good workout. whoever told you that is a moron.
I can hit you in the face with a 45lb plate and make you sore for weeks but it wont do dick shit for your hypertrophy.
Anyone can make themselves sore. Do squats with a 10 count pause inthe bottom position for 10 sets of 10 reps. Then do super sets of leg curls and leg extensions straight for 5min. I garuntee you will be sore! But it wasn't a productive training session.
Simply changing your exercises could make you sore.
Some get sorer then others. Some recover quicker. etc..
The main thing you need to look at is performance. If you are putting more weight on the bar when you come in the gym then you are doing something right and that is all you need to know. Whether you are sore or not means nothing. If you are performing on top of your game then you are moving in the right direction.
Always gauge your workout on peformance and how well you did compared to the last time and you will be fine.