Yong Heng Oil level rising

I bought a Yong Heng compressor and did the whole maintenance routine of running the compressor without pressure for 15 mins and then changing out the oil before putting it under a load. I refill the oil to right above the red dot oil level indicator and ran the compressor for 20 mins to fill up my 45min SCBA tank. When I went to de-pressurize the unit and turn it off, I notice the oil level was above the oil indicator by quite a bit. What's going on here? Am i getting water into the oil somehow?
 
I over filled mine the first time cause the sight didnt have the hole at the 12 o'clock position and kept a bubble there and looked like I needed to ad more. So make sure you have a hole at the 12 o'clock position like this

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