I'm a 16M (10:3*, 4:5*, 2:1*) that's previously trained at 20-30 mpw for the past few years. This is my winter base phase. I'm starting to do longer runs, and I did 34 miles this week. During two of my longer runs, I noticed some general pain in my feet. It didn't hinder my running, and it tends to come later in the run (after ~4-6 miles). I just recently got new shoes, but they're much better than my old ones, so I don't think I can pin the blame on them. Is this something I should be worried about? How do I counteract this if so?