Girl withdraws after sex?

I (29/m) have been seeing this girl (25/f) for 3 weeks before she suggested we go on a weekend trip together. We had sex on the night we stayed over, but the next day things became strange. While driving she refused me to have my hand rest on her thigh and she wanted to go home earlier than expected and did not want to be dropped right at her door step but instead a 5 min walk away from home. The next day she completely ignored my messages until night, claiming to be sick, not wanting to speak to anyone and rejected my idea of bringing soup and medication to her home. Am I over-reacting or is this unusual?
Updates
+1 y
She appears to enjoy herself during sex, very loud moans and claws into my arm, and kept kissing really intensely after sex.
Updates
+1 y
This is the first time we had sex
Girl withdraws after sex?
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