[Kean]

Sure looks like oil to me (tell tale sign of a leaky HG as @bman400 said) but I'd go the route of cleaning it out well and seeing if it returns like @donkpow mentioned. .....paying particularly close attention to it from now on (checking often).

To be honest, I'd be tempted to drain the coolant (if it were me) to check to see what's in the system.

 

[Kean]

https://www.roadandtrack.com/car-culture/videos/a30249/why-you-shouldnt-warm-up-your-car/

Unless the manufacturer is telling me different, on any normal day I'm not going to sit and idle a modern, daily driven vehicle with engine management just to warm it up. .....at least any longer than it would take to settle in, put on my belt, check gauges, etc. over and get moving. I take it easy until everything gets up to temp including the transmission and rest of the drivetrain. ....special scenarios aside.

 

[Kean]

Well, as I said in the second sentence after that one quoted: ".....at least any longer than it would take to settle in, put on my belt, check gauges, etc. over and get moving. "