I put a new starter in my 2007 Tacoma about a month ago. In about 10% of starts, the starter continues to be driving the flywheel for about 5-10 sec even after the engine has started, which is evident by continuing the standard starter noise running in parallel to the regular engine sound. After that, it stops 'starting' and the engine runs as usual. Othee 90% of the time, this doesn't happen.
What could be the reason for this behavior and does it require attention? Why does it happen only sometimes?