Unusual CTX TIDs?

Lately I have noticed I have been getting some unusual TIDs that yielded surprises. One such example was a nice 12-18, but was hesitant to dig thinking it was likely trash. Bit since it was a pretty clean park I dug anyway and uncovered a nickel on top of a dime. I have also been sering a lot of zincolns ranging from 12-34 all the way up to 12-45. Has anyone experienced anything like this or is my machine going wacky?

Funny you mention this in a post. Lately I have been getting the same thing and I thought my machine was going haywire. Perhaps it is due to the moisture in the ground? I was out the other day and had 3 zincolns that all were 12-43, 1 at 12-44. Some were down to 12-34. It seems as though the zincolns depth when it was 12-43 and up were within 4" of the surface.