When I've gone on month long breaks and returned to smoking, there was anxiety, yes, but most of this was due to this feeling that, "What the fuck, I'm smoking pot again now, fuck this shit's illegal" and I'll constantly think that people in my neighborhood will know that I'm smoking weed and I'll even get paranoid about there being cops around...and yes, this is just regular medicinal grade weed I'm talking about doing this. Most of it I attribute to the propaganda on weed in this country - IT WORKS PEOPLE! Almost all of the anxiety I get when I come back to smoking is just because I've been brainwashed into thinking pot is evil because it is illegal...the anxiety goes away after about a week or two of smoking again...
Also, I used to have an amphetamine problem for a year and a half and I NEVER had anxiety from smoking weed before going through the amp addiction...so, at least in my case, I'd have to at least assume that that period in my life as far as drug use goes is a contributing factor to any anxiety I get from smoking weed after breaks now in some way.