Um, MDMA does not release serotonin to your spine. That's actually a widely believed myth about MDMA (proliferated by a botched psychological study on monkeys by an idiot named George Ricuarte
Ricaurte MDMA Research Controversy) Serotonin is a neurochemical, naturally present in your brain. it works with the neurotransmitters in your brain as a serotonin agonist (blocking the reuptake of serotonin in the synaptic cleft, so that the normal amount of SN that is usually recycled by your brain is retained, giving you those 'rolling' feelings of euphoria.)
As an answer to your question, yes, many people who try E will report feeling as if they are rolling while not actually on the drug, days to weeks after the first few times they tried E. This is a normal residual effect of the drug, and it will go away (not that I'd want it to). Many drugs give us residual effects, some are more social in their origins (such as weed), but most are biophysiological. Nothing to worry about.
I suggest you cherish those residual E moments, because they will not happen quite as often (if at all) if you begin doing E more often. For me and most people I know, MDMA loses its 'magic' after the 4th or 5th time you do it. And for the neurochemical reasons I mentioned above, you should not do E more than once a month because it takes your brain 6-8 weeks (like most psychoactive drugs) to fully recover from the depleted serotonin levels caused by the effect of the E. MDMA is by far, my favorite substance, and it has a lot of therapeutic potential in mental health services. Don't abuse it. It will lose it's effectiveness. I really only do E at raves, and only like 3-5 times a year. PLURR!!!