1. apt to notice and make much of trivial faults or defects; faultfinding; difficult to please.
2. proceeding from a faultfinding or caviling disposition: He could never praise without adding a captious remark.
3. apt or designed to ensnare or perplex, esp. in argument: captious questions.
1350–1400; ME capcious < L captiōsus sophistical, equiv. to capti ( ō ) a taking, hence, sophism ( see caption) + –ōsus -ous
1. carping, nitpicking, niggling, picky, testy.
I would seem captious were I to complain.
Source: Tales of the Dying Earth by Jack Vance.