Medical mystery.

This is driving me nuts, I've Googled for hours but can't find an answer so hoping we have a few medical peeps on here. Ok, here goes: I slipped with a screwdriver today and it went into my left hand index finger to a depth of around 4-5 mm. It bled profusely so I quickly ran to the bathroom and stuck it under the tap. Although I thought it may need stitches I wanted to finish my project, so I wrapped a few plasters around it and finished the job in hand. Four hours later I sat down with 'er indoors and told her what I'd done as I carefully removed the plasters to see if I was going to get away with not going to the hospital. I didnt really want to look, but when I did I couldnt believe what I saw...NOTHING, except a small red mark where the screwdriver had entered. No pain, no soreness, no cut. So, has anyone seen or heard of such an occurence? Google says 10 days minimum on a young fit person...I'm 66, one and a bit lung and painfully thin.