1) I have put brand new Olfa blades in my cutter and they have skipped one or two threads. The 'skip' was always at the same interval - so even 'good' blades can be problematic at times.
2) Put a new, good blade in your cutter. Using less pressure while cutting should save on wear and tear on your mat. (My DGDs were cutting something once - and put some grooves in my mats - bless their little hearts) Use only as much pressure as needed to cut (with a SHARP) blade - no need to plow a furrow with it.