Trans might be slipping?
 

2007 Mazda 3i Touring, Sport A/T

Not sure what's up, when cruising at highway speed if I lightly press the pedal to accelerate, the RPM's smoothly climb to 6K and then drop back - and then the car accelerates. The car doesn't speed up until the RPM's drop back down. There is no hard "clunk" or any other noise involved. It almost feels like it's slipping - I've checked, and the trans fluid level is good. It doesn't happen all the time, and try as I might, I can't just make it happen.

Are there any known issues with the trans?
Has anyone else experienced this?
Other than the fluid level, what should I check next?

Mileage?
Ever change your tranny fluid?
Slippage means heat, heat means a shorter life, so over a period of time you’re going to shorten the life of your transmission.
READ: Flush it or Forget it | MotorWeek
AND: How often should the automatic transmission fluid... — Yahoo! Autos

Some highlights: every 20 degree increase in operating temperature above 175 degrees F. cuts the life of the fluid in half! At 195 degrees F., for instance, fluid life is reduced to 50,000 miles. At 220 degrees, which is commonly encountered in many transmissions, the fluid is only good for about 25,000 miles.

I have 60,000 km on my vehicle and have already had the tranny replaced. When it was replaced I had an external tranny cooler installed. After driving on new tranny for 20,000 km or so i had it flushed and filled with compatible synthetic fluid. They also gave me a lifetime tranny warranty for around $2,500 for getting this done at transmission shop. In another 50,000 km form my last change i am due for another flush & fill.

115K miles on the car.
Fluid was changed 3K miles ago

was the fluid changed before that, or was that the first time?.

No idea, I had it flushed when I bought it - 3K miles ago

I guess you have your answer. The pitfalls of buying a used car with no service history.

Problem solved!!!

I spoke to the owner of the garage that did the flush, and it looks like the mech didn't use the proper fluid (they don't keep M-V on hand).
Did another flush and fill with the proper fluid and the trans runs great now!