Yes, it is possible that it had too much fluid. You probably would not have known that untill you hit the higher RPMs.

I have seen this before. I'm a Test Engineer for a OEM transmission re-manufacturer. If the transmission is overfilled, it pukes out the breather tube, but not untill it hits high rpm.

While I have not personally looked for a breather tube under my truck, it should have one. There has to be a way to vent the extra pressure from the expansion of the fluid. Yet another reason to stay out of deep water. Water causes de-lamination of frictions in the clutches which means.... your transmission is toast.... literally. But I digress.

Be sure re-check your fluid level again and since you had it at high RPM for what I take was an extended period of time, check it for overtemp. You know, burned, discolored ATF. That is provided it is not leaking now, if it is, get it to a qualified technician.