I know this is kind of old now, but I have to do this a lot...I have a tendency to smack the space bar pretty damned quickly after I hit the last note on my guitar/bass/vocal...whatever. This is a reflex I've developed as a result of trying to record in a house full of small children...if by some miracle, I'm able to actually get part of a take accomplished without a door being slammed or a child screaming at one of his siblings at the top of his lungs, I'm not pressing my luck any further than I have to, lmao.
FF to the end of the file. "Generate silence" (I do 4 seconds)...that covers any tails I've ever needed to add. Oh, but don't forget to save it as a new file once you do this, and hit "insert in multitrack," otherwise...the file will still cut off at the point that it did in the multi-track session before you elongated it.
Nice fucking avatar, btw.