When somebody gets tow to pits, CC sometimes announce him as new race leader.
From sim/track perspective he is indeed the car most in front at that moment, which is probably cause of this message. Maybe CC needs to check also info, if the car is in pits and in case yes, not announcing him as a new race leader.
Btw. might be also nice feature to announce who enters pit (either towed or the regular way). In case of regular pit stop, optionally also time spent in pit stop might be announced.