Both Uses

phase
in
Nogin
(Edited)

That was either a phase or a ploy to get attention and drive Cindy crazy.
p. 117.4 *

phase = a period of time or a stage during the development of something
Maybe we all think we're gay at one point or another? That's how I rationalized it for so long. ... it's like I wanted so badly for it to be a phase and I convinced myself that if I made it one, then it was one.
p. 192.2

Definitions:

(1) (phase as in: a critical phase)
a period of time or a stage during the development of something
(2) (phase as in: she's going through a phase)
a period of time when someone exhibits unusual behavior
(3) (phase as in: phased out over three years)
make a change gradually (phase in = gradually add; phase out = gradually removed)
(4) (meaning too rare to warrant focus)
More specialized and less common senses of the word are found in astronomy, physics, chemistry, and zoology. Consult a comprehensive dictionary if you wish to see those. All senses have to do with stages or periods of time.