Hey, all. Ark-a-rific here in the sogged East. So I finally cleaned and restrung my beater acoustic., a Sigma DM 18. (Good grief, the fretboard gunk looked like demonic tar.) Mended a crack, etc. It now looks like Neil Young didn't try to hug it. Put on new strings in the same gauge of the prior ones (medium)--and now it seems disagreeable, intonation-wise. For those moments when the new strings which I've been diligent stretching, actually are in tune, it actually isn't. The A and B strings just do not want to agree with each other, no matter what and where, even when the A and B agree with all other strings. Before restringing it, it intonated perfectly. So my question is did I damage the neck somehow, or might the truss rod need adjustment, due to just changing strings? Or is this apparently now-innate problem just a temporary thing that will likely resolve once the new strings get more evenly stretched out? Thanks for your advice here.