My co workers Mazda 3 did the same thing, he ended up getting a new clutch under warrenty. I Dont exactly recall what was wrong but i think he experienced excessive clutch wear and he is a pretty good driver in terms of clutch riding.
His pedal was fairly heavy before and after the replacement it was pretty light.
High clutch engagement is generally something that happens when the clutch starts to wear out. BMW came out with a SAC to prevent that (self adjusting clutch) where the pressureplate compensates for wear. To my knowledge i dont think the mazda has this.
I would check for visual leaks, perhaps your slave cylinder is leaking or one of the lines going to it is leaking.
Depending on your mileage i would take it back to the dealership and have them look at it. It may be covered under your powertrain warrenty still depending on what it is.
I will add, a lot of people seem to complain about clutch engagement on the MS3/Mazda3.
AFAIK its not adjustble in the MS3/3 only in the MS6