In two separate articles on Wikipedia, the following claim is made:
Actor and pilot Michael Dorn owned a T-33. Dorn, who played the character Worf in the TV series Star Trek: The Next Generation and Star Trek: Deep Space Nine, jokingly referred to the aircraft as his 'starship'.
Dorn is also an accomplished pilot who owns and operates a Lockheed T-33 trainer jet, which he jokingly refers to as his "starship".
No source is given in either case.
It's also on Memory Alpha:
Dorn is an accomplished pilot and owns and operates an old Air Force T-33 trainer jet, one of the first jet aircraft in the US inventory; it is often referred to as his "starship."
Again, there is no source given.
Presumably the reason why he would call it a starship would be because of his work on Star Trek: The Next Generation and Star Trek: Deep Space Nine. But I can't seem to find a source for this.
Did Michael Dorn ever refer to his plane as a starship?