Did I Do The Right Thing? (drowsy Driver)

Hi. I was passing a car on the 401 early this morning and as I got closer they started to drift into my lane and almost hit me. I stay behind them and follow them to see if they continue to drive dangerously. They failed to remain in their lane two/three times, stopped 10m before a red light, signaled that they were turning but continued straight, and speeding down residential streets. I called the police thinking she might be drunk. She pulls into her driveway and goes inside. The police show up and talk to her. He said she was not drunk and probably just tired. I figured the false signaling and speeding might be because she realized I was following her. Should I have called the police or was this a waste of their time? Thanks.

Nope. Good call. She may not have been drunk this time but those indicators definitely required checking up on.

ditto on the above