rush of air when bottling

So I just bottled my fifth batch, and I'm finally getting around to ask this question. I don't think it's significant, but I'm wondering if I'm the only one who gets this.

My bottling setup is a bottling bucket with short PVC tubing connecting a fermtech bottler to the spigot. I also installed a 90 degree PVC elbow as a dip tube (thanks Revvy!).

When I first push the fermtech down into the bottle, I get this quick little rush of air out of the spigot. It lasts a second and it's gone. It gets less and less as I bottle, but it takes a case or so before it's gone.

All it really causes is about half of the top of the beer to have some bubbles, so I really don't think it's enough air to cause concern. But I'm curious because I can't seem to find anyone else who gets this. From the dip tube maybe? Would you guys worry about it, or let it go? Thanks

i have a similar issue, I worry about oxidation but so far nothing has tasted stale...knock on wood...

There must be air in the line - it's all physics via liquids. I'm not familiar with the fermtech but I get a similar bubble of air when siphoning out of my primary. The bubble forms a few inches downstream from the racking cane and is remedied easily buy pinching the tubing briefly right above it.