I'm going to go out on a limb here.
Mahogany is the wood that the neck and body of the guitar is made of. Rosewood is the wood that the fretboard is made of. If you look at your guitar you'll see how the fretboard is a different piece of wood stuck onto the neck.
Your neck could be bending because of bad manufacturing, bad stringing, or humidity changes. 2 times in 6 months is no joke. If it's a manufacturing issue get the guitar replaced.
Whatever you do, don't get manipulated into selling your guitar off and buying a new one from your tutor, until you know why it's warping, whether anything can be done about it, and why the tutor wants the guitar.
Everything's Eventual (tm)
Scarborough Fair/Canticle (Cover)