Ed brought this to my attention after the target can rotation this morning. This gap is now covered by a He bag, but I got some photos before that was completed.
Just from a visual inspection, it looks like there might be a pretty thin gap between the beam and the target entrance window flange. Note that there is a bit of a lip behind the target window, so the real inner-diameter of the target entrance flange is a bit smaller than what it appears from the outside.
This isn't necessarily a problem -- but we should watch for evidence of scraping on the beam-left side of the target entrance flange.
The two photos are top-down snapshots of where the upstream beamline exit window and target entrance flange in the current configuration.