Training Day 1 Week 3

Nice refreshing run this morning. It was misty and sprinkling when I started off. About 1.25 miles in I saw something large in the trees moving towards me and I could hear it following me. My heart rate shot up from 155 to 161 and the hair on the back of my neck raised. Soon I was back on a street and focused again. I ended up with 3.5mi in 34:04. I took a shower and was still sweating afterward when I was drying off. Does this happens to anyone else?