Did you recently start your cycle ?

Believe it or not you generally get more inflammation on cycle than you do if you are a natty, steroids themselves cause more inflammation of the muscle. Its the reason why when you are natural you can often train a muscle more times per week than you can than when you are on cycle. That and also the fact you are now able to lift more on steroids than natural, so it takes the body longer to recover from a workout even though recovery is effectively now better. Ever heard the saying 'The stronger you become the more rest you need between training sessions'?

Hard to definitively pinpoint, but it's possible that since you are on cycle, you are working out harder and are actually contracting the muscle a bit more than you did while training prior to jumping on cycle. Even though your workout routine hasn't changed as you stated, you have gone up on weight as a result of being on cycle and have evidently gained some added strength, which in turn has allowed you to work out harder and hence why you are feeling more soreness.