I'm not sure how do you define this "relaxed" state. If you define it with the inspiration, urge or craving to do something rather than sitting, than it is possible that what you have is actually the hindrance called "restlessness". Funny, but I think it's not so hard to mistake restlessness for positive states, because in our modern thinking good mood is generally associated with activity.
From a Buddhist, especially meditative, point of view, the urge to activity (and consequently, the difficulty with meditation) arise from the mental state of dissatisfaction: we feel the need to do things, to get things or to become something because we are not satisfied with how we feel, what we have or who we are. With other words: doing, getting or becoming is a way to the mind to escape from the current conditions. I guess this is pretty much logical even from a secular viewpoint, just people don't really think about things like this, because the paradigm of compulsory activity and sense-pleasures is completely accepted and dominant.
So, in the sphere of "meditation", there is probably a lot more experience in the direction of happiness — and, consequently, in the direction of insight, and in the direction of losing the process what we call "I". For example, if you read the Cula-dukkhakkhandha Sutta (The Lesser Mass of Suffering):
"'In that case, Niganthas, I will question you in return. Answer as you like. What do you think: Can King Seniya Bimbisara of Magadha — without moving his body, without uttering a word — dwell sensitive to unalloyed pleasure for seven days & nights?'
"'... for six days & nights... for five days & nights... for a day & a night?'
"'Now, I — without moving my body, without uttering a word — can dwell sensitive to unalloyed pleasure for a day and a night... for two days & nights... for three... four... five... six... seven days & nights. So what do you think: That being the case, who dwells in greater pleasure: King Seniya Bimbisara of Magadha or me?'
"'That being the case, venerable Gotama dwells in greater pleasure than King Seniya Bimbisara of Magadha.'"http://www.accesstoinsight.org/tipitaka ... .than.html
If you are interested, you can read about the hindrances, for example, on the following pages:http://www.buddhanet.net/budsas/ebud/ebmed051.htmhttp://www.accesstoinsight.org/lib/auth ... el026.html
"Just as in the great ocean there is but one taste — the taste of salt — so in this Doctrine and Discipline there is but one taste — the taste of freedom"