ふとした ... => unexpected / incidental / little bitty N2
Expected
ふと => suddenly; accidentally; unexpectedly; unintentionally ~ N3
ふしがある => Seem N2
Speculation
いつか ... た => Formerly (At some point) N4
Time
~Vた + せつな => moment, instant, juncture N1
Beyond expectations
~こういうふう => like this N1
Means and methods
~みこみがたつ => have a good prospect N1
Expected
~且つ(かつ) => and N1
Line up, list
おもったら => just when; no sooner than ~ N2
Things do not match the prediction
(か)とおもうと / (か)とおもったら => just when; no sooner than ~ N2
Simultaneously
つつ => while; even though; despite ~ N2
~ふり(~振り)      => to pretend; to act as if N3