Should any 1675's date change slowly?

[powerfunk]

I'm kind of embarrassed for spending this much time on TRF and not noticing this sooner. Perhaps I've been in denial about my beloved root beer, an impulse buy from a couple years ago.

In any case, my 1675/3 changes its date slowly, starting at about 10:30pm. Basically, it's just like my wife's Air-King-Date, which has a caliber 1535 and is known to change its date gradually. I thought I remembered reading long ago about some early 1675's having that trait, but...maybe I'm crazy; I can't find anything about that now.

It ticks 5.5 bps, so it's not a 1560/1565 movement. It doesn't hack, so it's probably pre-1972 as I understand. Its 5.2m serial puts it at 1977, so yeah, kind of a red flag there too. It keeps good time, winds like butter, and has a good power reserve.

I remember the seller's pics appearing to have a 1575 movement (with "1570" bridge) as far as I could tell, but I was an even bigger novice at the time so who knows.

Are any 1675's supposed to have the slow, "non-clicky" date change? If not, could it be a symptom of needing a service? Or am I just living in Franken City? Thanks all!