After my battery died I have replaced it in Authorized Service Provider. This costs nearly 140$. However after replacement I noticed that the weight of my Macbook Pro Retina (Mid 2014) has been significantly increased. Is it something I should worry about or there is a chance that they put some not genuine battery into my device? Is there any way to check this? Has anyone had the same experience?
You can check what the weight of the MacBook Pro should be from Apple's specifications and compare with the current weight of your machine. If it turns out that your machine is heavier, you can then do something about it.