Female cockatiel – swelling near vent?

[G12sbmx]

Hi parrot lovers and Merry Christmas

I noticed some swelling near my female cockatiel’s vent area. She is active, perching, vocalizing normally, eating and drinking, and pooping fine.
No straining, no sitting on the cage floor, and behavior is normal. She has plenty of calcium available.
Could this just be hormonal or pre-egg swelling, or is there something else I should watch for?

Thanks.