Is it true that transplanted hair in the front may fall because there is a high concentration of DHT receptors in the scalp?

Hair follicles to be transplanted, are extracted from the areas of the head that are genetically resistant to balding, which is called the ‘safe donor area’. This area, which is considered as the primary source of donor hair that is used in hair transplantation, is located at the back of the head, a few inches above the nape of the neck.
The physical traits of hair follicles from the donor zone is dominant over the physical traits of the original scalp tissue.
This implies that when hair follicles are extracted from these regions and transplanted to the areas that need coverage, they will be showing the same bald-resistant traits and will therefore remain intact and not fall-out.

Grafts grow fine in the front of the scalp.  The transplanted follicles are not affected by DHT.  However, the native hair int he front is sensitive to DHT, so you can continue to lose native hair after a transplant. 

There is a donor area on the back of your head where we can harvest DHT proof follicles. When they are placed on the front of your head they are permanent. DHT has no effect on these follicles.

There is no truth to you are worried about. The is no more DHT in the frontal scalp than elsewhere and transplanted hairs are immune from the effects of DHT