I had never heard of this before now. I found an entry for the object, called "The Wedge of Auid", on RationalWiki and there is a more mundane theory as to the object's origin.
The wedge is simply a tooth from a modern day excavator bucket, the kind used by workers digging foundations for construction projects.
The results of metallurgical tests made on the wedge are consistent with modern 2000 series duralumin[wp] which oxidizes fairly rapidly, accounting for the aged appearance of the wedge, and which can be hardened[wp] to a degree similar to mild steel. Aluminum will not strike sparks as steel might, which makes the alloy desirable for service in environments with combustible gases or vapors, such as the coal mines that flourished for a while in Romania.
With a decline in coal mining, the excavators may be reasonably supposed to have been turned to other uses. It's extremely likely that one of these excavators lost a tooth while digging the hole in Aiud; someone unfamiliar with the machine found it in the sand near the mastodon bones, and assumed it to be an anachronism.
See many examples of excavator teeth, here, a number of which closely resemble the so-called "out-of-place" artifact.