You, sir, are doing your duty as a student. This is the argument I've been trying to make for years:
1. A CFI is NOT an authority figure, but authority shall be questioned
2. Anything a CFI tells youstates as fact should be able to be backed up by written fact somewhere. If its not, he's lyingnot doing his job and is potentially spreading mistruths or opinion as fact.
3. Just because your CFI told you something doesn't make it true - you should always back up what you're told with investigation to ensure that you were told the truth, and you should ALWAYS go back and let the CFI know if you he told you a half-truth or a lie, lest he continue spreading false information to other pilots.
#3 is how we get stuck with stupid CFIs and stupid pilots that believe that flying the step actually works, or that you can NEVER slip a C172 with full flaps, or that you can't log cross country if you don't fly direct to the destination.
Note - the OP is not a "stupid pilot," because he asked. However, I would then challenge him to go back, get the facts, and confront the CFI with the truth. If the CFI balks at it, he should come back here and post the CFI's name, so we can get a crack at correcting him. Anything less is irresponsible, because God only knows what else that CFI is spreading as truth.