I am attempting to make leg warmers. I already made one on 4 DPN’s and I have a seam that is not supposed to be there. The directions say co 40 join and then begin the twisted rib stitch for 1 1/2 inches and then begin the garter stitch. the twisted bib stitch seems ok but when I begin the garter stitch the stitches are not matching up where the tail is. I think when I’m casting on I just begin the twisted stitch thinking that is joining the stitches. Since the pattern specifies join should I be doing something else? 
Yes, joining is just starting to knit, so that’s fine. Garter stitch in the round leaves a jog because you’re actually knitting a spiral, so the end of the round is one stitch higher than the beginning. What you can do is slip the first st of the round, do a purl round, working that slipped st as a purl when you come back to the end of the round. Then slip the next st (the new beginning of the round) and knit around, knitting the slipped st. Repeat.
BTW, if you knit every stitch in the round, it makes stockinette, not garter. I can’t see a pattern start with ribbing then go to garter stitch, which is alternating purl and knit row in the round. If you’re supposed to be doing stockinette, don’t worry about the sts not lining up.
Sorry, made a mistake it is the stockinette stitch (knit one row purl the next). But by the stitches not lining up in that one place it is causing a seam. Is that normal? Because in the pattern it says it is supposed to be seamless.
Seamless means you don’t sew it up. What you may be getting is laddering, where the sts are pulling apart. Are you using dpns or a circ?
Read this article about how to avoid the ladders, can work for circs too - http://techknitting.blogspot.com/2007/04/how-to-avoid-ladders-on-dpns-double.html
Also when knitting in the round your work will twist slightly so it looks like your tail from the beginning of the work doesn’t line up with the beginning of your rows after awhile. Some of that has to do with the twist in the yarn and the way you knit the stitches. Most of that is eliminated when the work is done and you block.