Phal with one flower shriveling - behind a new bud

[ClassyK]

One of my phals has been in full bloom since Jan 1st (duel spike). Around Feb 1st it shot out and extra bud on one side and two on the other. The side with 1 fully opened no problem, the side with 2 one opened and I have one bud. Today I noticed the flower behind my bud shriveled, the bud looks fine and all my other flowers do as well (pics attached).

I'm a little concerned, I bought this one 2 winters ago with the flowers off but spikes still in tact, they didn't die off and I kept them. Last year it shot of shoots on the old spikes, maybe 3 flowers each. It then shot out a 3rd spike and I had a few more flowers on that. When that 3rd spike shot though it was followed by a root die off (I house them in clear pots to see). And I lost a few flowers.

My roots are looking good but I'm now nervous about what the shriveling flower means and if I might have a root die off again. Leaves look good, nothing else is visually concerning. I had a second phal form a new bud this last week, a month after fully blooming as well. All 5 of mine have been happy where they are, but this guy has thrown me for a loop for the second year and I'm curious on if has any ideas on what is going on with this guy.

[estación seca]

The plants look very healthy. Inadequate water can cause this but they don't look underwatered. Especially in winter, drafts and sudden temperature/humidity changes can cause bud loss. And ethylene gas from an improperly vented furnace or proximity to ripening bananas or apples will cause it.

[ClassyK]

Watering is what I would lean towards the most, maybe this one is just more sensitive? I have them all on a 1 week schedule. The new buds initially made me worry because when the 3rd spike happened last year I had a root die off. Definitely not a furnace thing. Draft wise the window is on the opposite side of the room. There are temp changes as it gets pretty cold here but I feel like I would expect that on multiple flowers of this or my other guys.

If it's watering is it weird that it was an established flower open over a month vs the bud? The bud doesn't look concerning, the flower on the left is one the just opened, I figured it would stop energy into the bud instead of the flower behind it. I may just need to be a lot more hyper vigilant with this one. My orchid to the left just popped a new bud this week after a full month of it's initial blooms, so they all seem happy overall which is why I was concerned.

[estación seca]

What do you mean by "pretty cold?" Phals are known for dropping flowers and buds when they get too cold. They are warm growers that can be kept alive and flowered in household conditions by experienced growers.

[ClassyK]

Winter occasionally dip down to 63 indoors in that room, generally around 70. All my phals are multiple years old(with me, in this room, in this exact location) with the exception of this one have had no issues with flowers. If it was cold, I would expect this on multiple orchids, or specificly multiple flowers on this orchid would I not? It is why I was leaning towards more sensitive to water.