I have done that many times without problem. Split the brew into two days, Just sanitized the lid and seal and refrigerated. Obviously, you do run an increased risk of infection.You didn't notice any tartness from the lactobacillus on the grains that survive the mash? The people I've spoken to who tried it thought it was noticeable.
I have not noticed any changes. However, most of my beers are hoppy and have only been brewing for a year or so. They taste good to me.