Bug or feature?

Status Quo
I've been running Quarry incursions trying to complete my challenges. Sometimes I get a basic (T0) room with bad options and so I ignore that Incursion, pop into a map, find alva, and take a look at my new options (always the same room though). To my knowledge this is allowable though please let me know if it's a violation and of course I will cut it out.

Bug
Sometimes when I open Alva's incursion in the map, instead of offering the same room I get offered a DIFFERENT room entirely.

Example
Today I started a new temple run.
Starting rooms included:
Apex
t0 - t0
Jewellery - Poison - Explosives
Sparing - t0 - t0 - Splinter
Guardhouse - entrance - Tempest

My first incursion turned the t0 next to sparing into a corruption chamber
My second incursion turned the top left t0 into a gemcutters
My third incursion offered me Poison Garden upgrade with a Strongbox alt. Instead I ran a Burial Chambers, found Alva... and she offered me a completely different room! The Jewellery room.

Is this a bug or a feature?

Not sure myself, but I just wanted to back this up saying I've experienced the same thing. Of course it won't switch rooms when I want it to. (Choice between poison garden and lightning room or something) But I've had it happen randomly if I skip an incursion, especially if I log out in between.