Should I be suspicious of a conference that invites me, a recently admitted graduate student, to be an invited speaker? I'm a recently-admitted student to graduate program, albeit possessing a considerable roster of research papers in known conferences and journals.

I'd just, recently, received an email from the chairman of this conference to deliver a technical presentation, as an invited speaker in the target field.

Typically, invited speakers are the well-known heroes in their field. I am, noticeably, ambitious enough to taste such experience, but this offer's made me suspicious about the credibility of the conference, to the bone.

Should I accept the offer?!
It seems it is a junk conference, which will not bring you anything, but waits for your money! 

Don't go, it is a waste of time, you will get nothing good from it, since no one really involved at a high level in your field will come.

It is not unusual for those kind of conferences to invite "anyone" as an invited speaker.