I made an offer on a house, and the owner went for it. Signed the Purchase &
Sales agreement.

The realtor is still showing the house, which I guess is normal? I'm just
slightly concerned. What if a party submits a bid significantly higher than
mine, the sellers & realtor have would obviously have incentive to go with
the higher bid. Is there any legal way they can do this? They would need to
nullify my contract I expect.

Does this ever happen? am I being paranoid?

Thanks,

Johnny B.