37.5 weeks contractions

Went for a long walk around the mall last night with my family. When we got home I started getting mild pains in my lower belly moving around to my lower back. Went to sleep, slept through them til about an hour ago. Pain is getting more uncomfortable in the same area. Now it's about 6-9 minutes apart. This is my second baby, but my first labor did not start this way ( started with my water breaking last time and it was a quick 4 hour labor). Does it sound like the real thing or did I overdue it on the walking last night?