Personally I wouldn't eat them, I'd throw them out, after all what are they worth a £1, is it worth taking a chance. Steam some more spuds, no salt, mash and add a knob of spread of some sort, a teaspoon of Boullion stock powder, teaspoon of Colmans mustard and grated cheese, finish off by whisking briskly with a fork, BOOTIFUL!!!
Minimal boiling, very little salt but no stock powder and no mustard. My wife and I both like our food to taste natural (bland, some would say), so never use herbs etc.
I'm pushing 70 and never had any sort of digestive problem (including indigestion), so I must be getting something right.
I'm the same generation, born in 40s raised in 50s married in the 60s, but am a trained chef, or was lol, I like a bit of adventure when cooking and use little salt. :)
I cook a big pan of mash for the freezer. Mashed with butter, I use an ice cream scoop, into portions, then freeze it. Then put into a food bag I find it really handy to have ready made portions.