have your doubts

have (one's) doubts (about someone or something)

To be wary or uncertain of someone or something. I know you really love this neighborhood, but I have my doubts. I do have my doubts about Brian—he just seems untrustworthy to me.
See also: doubt, have, someone
Farlex Dictionary of Idioms.

have your ˈdoubts (about something)

have reasons why you are not certain about whether something is good or whether something good will happen: I’ve had my doubts about his work since he joined the company. It may be all right. Personally, I have my doubts.
See also: doubt, have
Farlex Partner Idioms Dictionary
See also:
  • have (one's) doubts (about someone or something)
  • have doubts about
  • plant a/the seed of doubt (in someone's mind)
  • sow a/the seed of doubt (in someone's mind)
  • come up roses
  • cross-examine
  • cross-examine (someone)
  • examine
  • with reservations
  • second thoughts