Is it normal to have a little discomfort in stitch area 4 weeks post op?

It is not unusual to have too much sensation or too little sensation for the first month after surgery. With thigh lift, as you get more mobile it is possible for you to get more swelling which is associated with more discomfort in certain areas. However, you do want to make sure that you do not have a "stitch abscess" which is a local area of suture irritation with likely suture extrusion. Make sure you see your surgeon on regular basis and keep the area clean.

First of all, congratulations on your thigh lift, pkh80.
It’s only been four weeks since your thigh lift, so it’s normal to have some degree of irritation especially in your incision area. Just watch out for any redness, pus, or heat on the area, as those are signs of infection. Report those symptoms to your reputable and board-certified plastic surgeon if they show up.
As for the compression garment, just continue wearing it unless your surgeon says otherwise. Every plastic surgeon has his own protocol regarding its use.
Best of luck!