Heck I'm 32 and already played this one too conservatively. I sold some shares last year at 10 cents because I had been holding for 5 years, similarly to you, and 1) wanted to take some risk off the table, and 2)VTSI had become a majority of my portfolio and I figured I should diversify at least a little.
Of course now that sell at 10 cents looks completely foolish and I should have stuck with my convictions about VTSI's future.
I can't remember what great investor it was that said you only need one or two good ideas per year to be a great investor. VTSI was a great idea last year (and this).