Not to disparage your good group, but with only three shots there is a good probability of chance that increases in proportion to how accurate the rifle is. How about shooting a five shot group to rule-out chance.
Bench rest (and other competitions), competition established the standard of measurement at five shots (and in some cases, ten shot),. If you do not follow that convention, it is more difficult (comparison is not valid), to compare your group relative to five shot groups.
If someone wants to argue the fact, look-up the bench-rest record for three-shot groups.