Those are bermuda seed heads. The reason you have them in one area and not another is due to stress. It could be your sprinklers are not hitting those areas the same as others. Put some cat food or tuna cans in the yard, turn on the sprinklers, and time how long it takes to fill that cans. That is your target time for watering once the grass is knitted into the ground.

If you still get the seed heads, then you are not mowing frequently enough. When bermuda is really growing it should be mowed 2x per week at a height of 1-2 inches, watered once per week, and fertilized with a high N fertilizer once a month. That will keep it deep green and dense enough to keep weeds out.

Thanks, I believe you are right on with your assessment and suggestions.