wierdness while bottling...siphon started randomly. Crisis averted but WTF?

[culdeus]

So I'm getting ready to rack from secondary to bucket.  I have my siphon down in the bottle and start to attach the hose to the siphon.  The act of adding the hose to the fully plunged in cane and :shock: beer starts coming out.  I lost about 8 oz to the floor, but managed to get the hose to the bucket in time. 

WTF happened?

[Kegergator]

Was there any kind of fluid in the tubing to drain down as you attached it? That could have cause a siphon.