A 1957 D/D/D RPM with a twist-error ? Opinions please

I have been a Lincoln variety hunter for a very long time and this one has had
me baffled so I would appreciate any thoughts or opinions.
The 1957 D/D/D RPM-3 is a CONECA Top 100 variety so it is nice in and of itself, but
take a look at this a little closer.
Is that a 7 hiding behind the 5 ?
I believe the 50's era Lincoln master dies were pre-punched with the 19 but not the last
2 digits of the year. Could it be possible that a stray 7 was hit into the die in error ?
Some coins are just plain "Interesting"
0
Comments
You have a shot...anyway, I'll suggest that you get the green crud off the coin!
From what I understand, the 1 and 9 remained from year to year, and only the last two numbers of the date were engraved every year change.
I don't know what that could be sticking out of the 5 in the date.
Pete
Different lighting angle

Whoa. That's something you don't normally see... cute and interesting..!!
Definitely something there... not sure what... would not have thought a seven though.... Cheers, RickO
Sweet. I double checked mine but there is nothing on it. I thought maybe a later die state (VV has an unconfirmed stage E) but yours is A-C without the die break in Liberty. Interesting for sure.
"You Suck Award" - February, 2015
Discoverer of 1919 Mercury Dime DDO - FS-101
Certainly gives one the impression that a '7' could be lurking there. Anyone else with a RPM-3 to compare? Or is it just unique to your coin?
Never thought about that......good idea.
Pete
Here's an image of one (ANACS 64 RED) I sold in May 2017. Though the image isn't super clear, I don't see a even a hint of anything by the 5 in the position noted on the OP's coin:
Thanks for all the thoughts and opinions guys.
It is greatly appreciated especially from such a pretty smart group.
I will dig the coin out of storage and try to get better pics and do some overlays.
If I can come up with anything one way or the other I will add it here.