Getting air in my well water line

I have a Grundfos submersible pump that I installed last may. It has a built in check valve, and it has worked fine until yesterday. Yesterday evening my wife tells me she flushed the commode and it sounded as if it was blowing up. She said she flushed it again and got a shot of dirty looking water. This morning she was adding water to the pool and got air and another shot of dirty water. I turned off the pump and drained the pressure tank. I put the drain hose into the floor drain and turned the water on and walked away. The hose was in the drain to the bottom, 17 inches deep. When I came back there was water on the floor and the hose end was several feet from the drain.
It look like the hose had blown back out of the drain and water had been sprayed on the walls.It appeared that there was alot of air at the end of the draining and the hose blew back out of the drain. The tank pressure was 35, so I bumped it to 38. (40/60 pressure switch)
I went to the well and measured down to the water level. The well is 80 feet deep, cased 60 feet(6inch case). The pump is 44 feet below the adapter, and the water head is 30 feet above the pump. I watched the level in the well through several cycles.
It never dropped below the pump. It appears that I am getting the most air when the pump first starts. After the pump stops and things settle down, I can bleed the outlets and things seem to be fine until the pump starts again. Does anyone think that the check valve at the pump is not working properly. Any ideas about what my problem could be? Any help is appreciated.

Do you have a second check valve at the tank or does the line to the pump stay under pressure? Was this originally setup with a snifter/bleeder?

You may have an airmaker system and you're air release has gone bad, thus the excess air getting into your lines. Do you have a regular galv. tank or a bladder tank?

There's to many unknowns here for me to make a qualified determination. You shouldn't be getting air or dirty water. Dirty water is sometimes caused by water a check valve allowing water to run back into the well. Air in the system can be caused by a leak in the drop pipe when there are more that one check valve at the line.

There is a second check valve at the tank. The check valve at the tank has been there 31 years.
Unfortunately, the check valve is the first fitting attached to the line from outside. It then attaches to a 1"x1"x3/4" reducing tee. The 1" to the bladder tank and the 3/4" is all sweated copper. You guessed it, no union! I suppose this check valve only checks from the tank to the wall, about 7 feet of line. I guess in theory the pump check would check from the pump to the check inside the house. For some strange reason, I have had no more air since last night. I suppose it is possible for the check to hang and then somehow free itself. Any thoughts?

If the check valve on the pump leaks and the one at the tank holds, the water falls back by weight and creates a vacuum. If there is a leak in the line, the vacuum will pull air into the pipe. When the pump starts, the air is pushed to the tank.

Remove the check valve at the tank and rely only on the check valve in the pump. Find and fix the leak in the line.

Thanks for your advice. As I mentioned earlier, today I have had zero air issues. I am guessing that if the issue was check valve related, it has somehow corrected itself.
The line in the well from the pitless adapter to the pump is one year old poly pipe.
I suppose it is possible to suck air around the adapter. The line from the casing to the house is 30 year old galvanized, three feet deep. I will wait and see if the issue happens again in the near future.