That's an accurate assessment.
Take a look at the raised border on old Hard Rubber grips - and the newer plastic ones, as well - and look at how their raised borders butt agaist the edges of the frame, backstrap and triggerguard.
You'll see quite a bit of differences in thickness there, because that's what the factory added for individual fitting.
A set of Colt grips should fit without a raised edge along the edges - they should feel seamless to the touch, without gaps or warping or any other anomaly.
Vaya,
Scouts Out!