Deli style roast beef will react to a stainless steel slicer blade sometimes. I retired from the school food service here and we had to slice and use the beef immediately. With all the preservatives in lunch meat it's highly unlikely especially at a high volume restaurant like Subway that the meat had gone bad. Visually,not too appealing regardless. On the road we use Subway a bunch.
I could be wrong, but I believe their meats & cheeses come in pre sliced. I've NEVER seen a slicer there.
I'm also not too good at late night greasy food anymore either. I'm NOT a night person, wife is. Sometimes we end up eating dinner 8-9 at night. Those nights I'll opt for a bowl of oatmeal or grits.