Wild yeast accidental ferment

[sundaypapers]

On Saturday I brewed two beers, as usual, the first an IPA, 1.078 with 4 oz of hops, chilled with wort chiller to 80, put in sanitized carboy and covered with sanitized foil and left to chill in my fridge. The 2nd a hef went through the same process. Normally it isn't a rainy day, but that day it rained a little and was a little windy. Anyway, I left the hef in the fridge and took the IPA out, mini fridge, and today, Sunday evening, I saw the IPA fermenting already. My yeast wasn't yet pitched, starter still going on the counter, carboy temp 71.
This is a process that I have done for over 30 batches, cooling one and fermenting the other, then fermenting after the first is finished or coming close, taking it out of the fridge and ramping it up. Carboys are always cleaned and sanitized, transfer from keggle to carboy is with a vinyl tube sanitized with foil over the carboy opening, so I don't expect much to get in that way. Only thing I can think is that toward the end of my chilling something got in and made a stronghold. The beer was in a Carboy at about 9am, so in 36 hours seeing active signs of fermentation with no starter, or yeast for that matter, seems really odd. Especially given the gravity. I've had bigger starters take longer to get going.
Anyway, I pitched my starter on top, half gallon of us05 slurry, and lowered the temp to 66-67, so il see what happens. I just keep thinking that it's really weird and that maybe this was a wild super yeast that blew in on a breeze, like it was meant to be.
Anyone have an experience similar to that? I smelled the beer and it smells fine, but I don't know how long it would take for an off flavor from wild yeast to show up. It is definitely going strong though. I don't know what to expect, but I'm along for the ride...

 

[sundaypapers]

The keggle is welded and wort is transferred via ball valve. I cover the top opening during transfer, but isn't realistic to cover during chilling, immersion chiller.

 

[twistedjosh]

If it was a Brettanomyces strain, it will ferment out and taste and smell like a clean ale yeast at first, but as time goes on the funk will start to come around

 

[sundaypapers]

Interesting. I'm planning on drinking them quick, but I may keep the cake and just see what happens pitching it again. I was more worried about how quick it took off than anything else...haven't seen that happen very often at 36 hours. Thanks for the info, never worked with Brett, or any funky/sour strain before. I was just wondering what to expect, but it seems like I can expect anything.