Springs do weaken from being loaded.
It may still "function" like the reports of the 30 year old mags still working.
But it willl be be pushing up those rounds very slowly, and in a couple more trips to the range may fail.
For heavens sake, once every 5 years or so, spend $5 bucks and get a new spring.
You don't have to get an entire new mag or follower if you don't want, but
a cheap spring is easy to replace and good insurance.
People spend $20 for .01 ounce of the latest gun lube every 6 months,( which is probably not needed), $1000 a year on the best bullets, but won't replace a $5 spring every 5 years.