pump pressure question

Last year was our first season with our 24' above ground pool. The pressure stayed at 15 unless it needed backwashed then it would get higher we would back wash and then it would go down again. This year since start up its been at about 22 or 24 , it goes up to 30 and once or twice over 30 and we backwashed and it drops back down to the 22 or 24 but not back down lower like it was last year. Does anyone know what this means? Thanks in advance.
Oh the pump is a hayward... sand filter S180T1580 seriesb 1.5 HP

The first thought is a bad pressure gauge. They are notoriously unreliable.

If it's not what John said (that would be my first guess also), there is some restriction that's been added between the pump and the return lines to the pool. That could be an old tennis shoe (:D ), a new device, replumbing, etc. ............anything that would restrict the flow back to the pool.

I'd replace the guage first, and if that doesn't do it, find that restriction.

Thanks to both of you for your thoughts on this,, I guess I am going to be making another trip to the pool store, LOL!! Unless I can get the gauge somewhere else?
Again thank you for your help!