Last year I bought 2x6 cedar decking. I stained it (two coats) front and back and stacked it in my garage with spacer between each row for air flow. It stayed in garage for 9 months. Two weeks ago I played the deck. Then I used thompsons clear water seal to finish it off. After the speaker started to dry I noticed a oil looking substance laying on the boards in spots. It wipes up clear and has no odor. Do you have any idea what's happening.??