my 610 is mooing

Today I was at a friends place and we were standing outside looking at the 610 and it kept buzzing, a short buzz once every three minutes or so.
The bike was off with the key off.
Sounded maybe like a motor or something.
Really the bike sounded like a cow mooing...

Any ideas?

the moo is weird and normal. It's the valve on the tank vent.

I was ignoring it, so as not to admit my insanity.

It does sound like one of those little round boxes that make a cow noise…
Can you imagine a bunch of 610’s together after a ride ?

Next Husky gathering somebody needs to take a video of that

Thanks Guys,
I sat the bike outside in the sun today and having been completely quiet all morning it started mooing again once the sun started to warm the bike.

I can see that's going to get annoying come summertime.