Is there any blade play or wobble? If not, I wouldn't worry about it. The liner/backspring gaps I've found on some of my old U.S. Schrades aren't too bad. (The liner/backspring gaps on many of my old U.S. Camillus knives are worse, but I usually can use feeler gauges and clean them out & close them up a little.) I haven't been able to reduce the gaps on any of my old U.S. Schrades, though.
thx - cpr