NOT A TEACHER
(1) Yes, I believe that you are correct: you could use the past.
(2) But native speakers often like to use the present tense in conversations.
(3) Some books explain that it makes the conversation more "vivid." That is,
it makes the situation more personal and more immediate.
(4) So you often hear native speakers say something like:
I hear that you are getting married. Congratulations! (By using the present tense,
you more personally, emotionally, dramatically connect a past event with the
conversation that you are having NOW with someone.)
(5) "Derrick says that you are acting weird."
(a) One book might explain it this way:
Derrick has said that you are acting weird, and the speaker is now remembering
Derrick's words. (Credit: English Review Grammar by Walter Kay Smart.)
(6) I know that it is very confusing. Learners always ask about this matter. If you have
more questions, just post them. The great teachers will be happy to help you.
Student or Learner