The 49ers announced Sunday night they fired Jim Tomsula, who got one year in San Francisco to replace Jim Harbaugh before being canned. 

And his old boss, now the coach at Michigan (where he won 10 games) appears to have a well-timed tweet about his old employer and/or the man who replaced him.

At 9:57 p.m. ET the 49ers tweeted out the news about Tomsula's firing. 

Almost exactly an hour later, at 10:58 p.m. ET, Harbaugh sent a message to the Twitterati that feels very much aimed in the direction of San Francisco.

There is a very good life lesson here. People often do reap what they sow! 

The question remains as to who this is being directed at. Is it a shot at the 49ers for getting what they deserved by running him out of town, despite three-straight NFC Championship Game appearances?

Is it a shot at Tomsula, who many believe may have undermined Harbaugh during the stretch run of his tenure in San Francisco? 

Or is it possibly a shot at anyone thinking about going to coach the 49ers, alerting them as to what will happen if you get in bed with the crew in San Francisco? 

The third option feels like perhaps reading a little too deeply into things, and maybe, just maybe Harbaugh is only passing convenient life lessons. But it sure feels like he took an opportunity, after staying largely quiet for a year, to put the 49ers and Tomsula on notice.

Jim Tomsula is out after a single season. (USATSI)