Closed-lid Macbook pro (2018) heated-up inside my carrying bag

Dear Community:

I have bought my macbook pro 2018 15" Touchbar edition just a month ago in S. Korea and I'm very new to the mac-world. But I have long experiences with windows laptops. By the way, lately I found some heating issues when I was carrying the macbook inside my bag while it was in the sleep state. After an hour or so, when I returned to my home and was taking it out of my bag, I observed that my macbook way too much overheated than any given times. Then, I thought may be I have to turn it off before carrying and I tried that the next time and it worked! Today, I forgot to turn it off and carried it upto my home. This time, around 3 to 4 hours later, I again found my mac overheated while taking it out of my bag. But I found my mac was still in sleep state.

I checked an answer in this community dated back to 6/7 years earlier which says- it's not to worry about while carrying mac if it is in sleep mode. Then, what else could be responsible for such overheating issues? Do I have to check some settings, especially related to those of bluetooth devices. Should I need to turn off the feature "allow bluetooth devices to wake up computer"? I do have magic mouse 2 (bluetooth) which I usually do not turn off.

I am kinda worried that, overheating to such extent may cause internal damage to the machine.

I would definitely appreciate any help in this manner.

Thanks a lot.

Mahboob