The lower frequency is typical of the Rock-mights too.
In most circuits with parallel resonant crystals, a series capacitor/trimmer will raise the frequency. An inductor in series will lower the frequency.
Series resonant crystals such as the 7114s from ESS will be higher than the marked frequecy.
A combination of trimmer and inductor in series can be arranged to both raise and lower the frqeuency.
There are examples of such circuits in the W1FB's QRP Notebooks and in EMRFD.
Chuck Carpenter, W5USJ
EM22cv, Rains Co. TX