Sun exposure for FUE Hair Transplant - 3.5 months post op.

Sun exposure is not recommended after surgery as it can cause skin discoloration.  If it is a bad sunburn then it may affect wound healing.

At this point after your procedure it is unlikely that this exposure had any effect on the growth of grafts-although of course the skin can be injured just like with any sunburn.In the first 1-2 months post procedure excessive sun may lead to slight pigment changes in the area.I think you will be fine.

While it's obviously never a good idea to get a sunburn, your grafts should be fine. After a month or two your transplanted hair is fully established so they won't be harmed by any normal means- really just some intense trauma that'd affect normal hair too will affect them at this point. Just keep in mind that for a while following a transplant the skin in the area will likely be sensitive to things like sunburns, etc. 

Excessive sun exposure should be avoided. Their are two main risks involved after having sun exposure. The first is post inflammatory hyper pigmentation and the second is an inflammatory response of inflammation to the scalp that can cause some hair loss. Chances are that you will be fine, but in the future be more cautious.

Sun seems to play the biggest role in the healing in the first 6 weeks after transplant. At 3.5 months, it would be very unlikely the hour of sun changed your outcome.  Likely, you are still in telogen, and you will see new growth in the coming weeks.  

It is never a good idea to expose the recipient area to sun as sun with its ultraviolet light can damage wound healing