Post-power failure - bladder tank lost pressure - time to replace?

We had six days of power loss here in CT - when the power finally came back on, I noticed the pump was cycling on and off almost continuously.

Specifically, my first shower, I noticed the pressure would decrease and then increase noticeably (with the lights flickering slightly) -- this happened about 8 or 9 times during a shower. I went down and checked and sure enough the pump was cycling on and off every time any amount of water was used.

I drained the system and measured the pressure in my bladder tank -- 18 psi. My pressure switch is 40/60, so this was obviously not good. I charged it back up to 39ish and everything seems to be fine - pressure lasts a good few minutes of heavy use (sink and showers running) before the pump comes back on.

MY QUESTION -- should I be concerned that the bladder lost pressure during the outage? Why did it lose so much air -- isn't it supposed to be airtight? Does this indicate a problem or some kind of slow-leak with my tank?

In other words - should I seriously consider replacing the tank soon, or is this kind of thing normal? Tank is about 20 years old and seemed to be working OK before the power failure. I'm not in a hurry to spend money, but on the other hand, I'd rather not be forced into a replacement once the thing bursts (I'm sure it won't be convenient then), and if this is a sign that it's about to die, I'll bite the bullet and replace it.

All thoughts welcome, thanks.

What brand of tank is it? Some tanks like the WellMate have a bag instead of a bladder. The bag is completely surronded by water, and the air charge can't get out of a bad bag as long as the water side has pressure in it. When the power goes off and the water side has no pressure, the air in the bag can leak out.

Thanks, it's an Amtrol Well X-Trol WX-203 (32 gallon).

It's got a fair amount of exterior rust - I suspect it's the original tank installed when the house was built (1981-ish).

What do you think of the WellMate as a replacement candidate? It's pretty humid down in my plumbing corner of the basement, and composite seems a better choice than steel - are they reasonably durable?

The WellMate is a good tank. When is a humid area or buried and steel won't last, the best fiberglass tank is the Well Mate.

Valveman, thanks, I'll consider that when shopping for a tank. So far, I'm doing ok with this old one, after I charged it up.

I'm considering also adding a cycle-stop valve to protect the longevity of my new-ish pump, which I had replaced last year. If I'm running a 40/60 pressure switch do I get the 40, 50, or 60 psi version?

With a 40/60 switch you need a CSV that works at 50 PSI.