Expiration date on FAA tailwheel / complex endorsement valid?
I recently noticed that my tailwheel and complex endorsements in my logbook have an expiration date on them (about 2 years after issuing date). Both endorsements were issued by an FAA instructor, I have an FAA pilot's license, and I was not a student pilot at the time of issuance.
I was under the impression that FAA tailwheel and complex endorsements do never expire, and I have never heard of time-restriced tailwheel and complex endorsements.
So is this probably a mistake of the instructor, or is he able to limit the validity of endorsements?
Will I have to get new endorsements without expiration, or can I safely (and legally) ignore the expiration date on the endorsements?