Why wont my tattoo artist respond to text messages?

I've gone to the same artist for the last year now, we have a standing appointment for the first week of each month I just message or text him and see if he's available on certain days and he usually gets back to me within two or three days but this month he has yet to contact me even though he posts on facebook that he has openings. It's really bothering me...I want to finish the unfinished tattoo I have by him but if he doesn't respond soon I'll have to find someone else to do it which is hard to do especially where I live where all the artists suck or do too many drugs to do steady line work.