The last weekend reddick aka razorback was open I was doing a night ride, towards the last pit, i nose wheeleied a drop just a little too much and was sent flying over the bars and my bike tumbled violently down the slope. Took a brief visual survey and could see no damage, jumped on kept going. The next day I discovered that my brake lever put almost the identical dent you have in the top tube of my mamasita.
thats was 2007.
Its been almot two years since, the dent is still there and the bike although a little beat up is still going strong.
Its the mtb equivalent of a scar, no big deal structurally, just a cosmetic flaw.