Sounds rational to me, but make sure you ladder the due dates of those bonds since I don't think rates are going to stay that low for too long. I doubt they will go anytime soon to (for the 10 years) the 6% level either.
Apologies for not responding to some posts today, over the weekend I was quite busy putting some final touches on a patent for one of the "start ups" I am involved with, these things always squeeze the "juices" out of me (g).....