There are a couple of possibilities here. In order of likely-hood:
1. It's not an EVH, it's a Japanese-built (from US parts) Axis. You can still buy the EVH form-factor as an Axis from EB/MM Japan....
2. It's a fluke, a US EVH that came out at the very end of the run and didn't get the signature decal....
Either way I think it would SIGNIFICANTLY effect the value of the guitar... A Japanese EVH-style Axis is worth about the same as a contemporary Axis on the used market in North America (~$800), but I'm not sure what a real EVH would be worth sans the signature decal. Get the serial number and post it here and the Admins will be able to tell you if it is a US-made guitar.