i wasn't hammering on the accelerator btw...

I thought this was odd and so tested it to see if the engine was being weird or not, so i put it int 3rd, went a nice 30mph and slapped it in 5th gear.
Now the revs should go right down, however this was not the case, the revs stayed exactly the same and if i floored it, the car would carry on at 30 yet the revs would increase very quickly up to 6,000 which s extremely worrying
So i checked it again this morning and low and behold it was completely fine!!! and didn't stink of clutch.
Im almost certain there is something wrong here and as i dont know much at all about engines, clutches etc... could some1 tell me what has happened or experienced the same thing???
cheers
mike