As a huge bond bull I warned people for months to stay away from duration. This is why. The yield is great but duration risk can destroy years worth of yield if you are caught too far out on the curve.
I've been saying $IEF was the furthest out I was willing to go (around 6 years duration), but a few months back I went 100% $SGOV which is 0-3M t-bills.
We need to wait for rates to shake out a bit more before wading into the deep end of the pool. Just collect the 4-4.5% for now and chill.