Why are my butt and hamstrings/hips not sore several hours after squatting?

I have not done squats regularly lately but today I started out doing squats with bodyweight and have done 4-5 sets with 15-18 reps each. My quads and possibly butt and hamstrings were tight feeling immediately after the exercise but as the day went on a few more hours I don't feel tight or sore anymore. What is it that I am doing wrong with?

Why are my butt and hamstrings/hips not sore several hours after squatting?
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