I noticed for the first time today that my frog happily locks to the 30 and
31 Mhz ranges in the positions to the left of 29 Mhz on the dial. (All
ranges from 0-29 Mhz work just fine)

From a brief test, it appears the receiver is quite capable of tuning from
30-30.99 Mhz.
(The AM mode does an admirable job as a slope detector on narrow FM)

Sensitivity appears to be less than in the plated frequency range
(presumably some attenuation by preselector and the band pass filter for
band "D") but still quite usable.

So here are my questions,

Is this normal behaviour for an FRG-7, or does it indicate a problem ?

Would the long-term use of this "extra" receiving range have the potential
to cause problems for the receiver ?