Clenching and heavy sweating when coming up

>One of my buddies recently gave me some ecstasy that he brought back from a
>vacation. I kind of wigged out for a few moments: clenching, heavy
>sweats, wanting to be removed from the scene, but the rest of the evening
>was pretty positive - like a trippy sandwich with spoiled insides. Is this
>pretty typical or am I just a rookie?

Many people notice some physical side effects, particularly while 'coming up' including those you mention and also nausea. For most people, they are much less severe than you describe and are accepted without alarm or discomfort, but people do vary greatly in their response, so its wise to try a low dose first time.

People seldom complain after the drug has taken effect, but that may be simply that they are no longer aware of discomfort. I have known someone say she felt fine while clenching so hard that she chipped a piece off her tooth.

I believe that the effect of masking discomfort is one of the drug's principal dangers. So its wise not only to realise this yourself but to be with friends who look after each other, particularly with respect to overheating.