Did I Witness Someone Make a Bit of a Mistake?

The other day I was planespotting at Paine Field, in Mukilteo, WA USA. I was next to runway 16R. In the distance I could see aircraft landing and doing touch and goes on runway 16L. One of the landing aircraft, a Cessna 172 on approach to 16L did a very last minute go-around. However instead of flying the runway heading and then turning left crosswind, it turned right and overflew runway 16R at a relatively low altitude (~400-700ish feet agl). Is something like this normal? Or, is it likely that someone had an oopsies?

Also, about 30 seconds later, a different Cessna 172 landed on 16R. How dangerous could this have been?

There was also a Boeing 737 on downwind at the time. However, it took that aircraft several minutes to reach the airport, so I'm guessing that aircraft would not have an issue.

For context, the relevant details of KPAE are:

• Class D airport
• The published traffic pattern for runway 16L is always to the left
• The published traffic pattern for runway 16R is always to the right
• This was in the middle of the afternoon on a clear day