AMERICAN PRODUCTS TITAN DE POOL FILTER rusted out

Anyone ever had their stainless steel pool filter develop rust holes? I own an AMERICAN PRODUCTS TITAN DE POOL FILTER that is probably 20 years old. I've lived in this house for 5 years and it's worked great, but for some reason this year, when I went to open the pool I noticed that the pool filter tank had 20+ small round rust holes, thus making the filter totally unusable. The only thing that changed this year, was the fact that we got a ton of snow in the DC area this year. Could not cleaning the filter properly cause it to rust out? There are holes on the side, bottom and top of the unit.

I'm no expert on filters but my initial thought is that if you got 20 years out of it, you got your money's worth.