Your post really resonated with me for a couple of reasons. Just yesterday I was contemplating the very thing you mentioned, the cravings to be involved in a D/s relationship - the need really for an outlet for the experience and expression of the submissive nature. For me too it has been just over a year since my last involvement. I actually think the cravings you spoke of was what brought me here to the Library recently. I needed to at least feel a connection with others in the lifestyle. The other interesting thing is that I'm also a runner and running has helped me deal with these feelings too.
I never really lose touch with my submissive nature nor doubt that I am submissive even in the in between times when I don't have a person in my life to submit to, yet you do over time really began to long for that because I suppose we just aren't being all that we can be as a submissive when we aren't actively offering that for someone's benefit. So, yes I am definitely another one who has felt those cravings and believes them to be a perfectly normal part of who we are.