2002 Subaru Legacy Enginie Hesitation

My engine hesitates after I refuel but only does so briefly--maybe for about 2-3 minutes following refueling. I do tend to run my tank down nearly to empty and then fill completely up, but I have noticed that this does still occurr if I fuel at the half way mark, too.

Is it a clog in my fuel filter or my injector? I had all spark plugs changed 11 months ago and typically have my oil changed every 3,000. I haven't experimented with adding a fuel additive.