Huh? If you literally type '1/13' into the live demo it works as one would expect. '113' works too, it just assumes the month is eleven, and the year starts with 3.
Secondly, remember this is for credit card expirations and not normal dates. You can probably make an assumption that 11/30 (November 2030) isn't currently valid input either. I have never seen an expiration date further than 10 years in the future. Although more research on the topic would be needed to figure out the true restrictions.